Transcriber’s Notes

Obvious typographical errors have been silently corrected. Variations in hyphenation have been standardised but all other spelling, punctuation and accents remains unchanged.

The repetition of section titles on consecutive pages has been removed.

A reference to Monism as “destructive of culture, etc.” in the index to page 450, which does not exist, has been changed to 350.

THE CASE AGAINST EVOLUTION

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THE CASE AGAINST
EVOLUTION

BY

GEORGE BARRY O’TOOLE, Ph. D., S.T.D.
PROFESSOR OF THEOLOGY AND PROFESSOR EMERITUS OF PHILOSOPHY,
ST. VINCENT ARCHABBEY; PROFESSOR OF ANIMAL
BIOLOGY, SETON HILL COLLEGE

New York
THE MACMILLAN COMPANY
1926

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Copyright, 1925,
By THE MACMILLAN COMPANY.
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Published April, 1925.
Reprinted February, 1926.

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TO MY MOTHER

ADDENDA

Note to [page 23].—

As a result of recent investigations on the sex chromosomes and chromosome numbers in mammals, Theophilus S. Painter reaches the conclusions that polyploidy cannot be invoked to explain evolution within this class. After giving a table of chromosome numbers for 7 out of the 9 eutherian orders, Painter concludes: “The facts recorded above are of especial interest in that they indicate a unity of chromosome composition above the marsupial level and effectively dispose of the suggestion that extensive polyploidy may have occurred within this subclass.

“In the marsupials the chromosome number is a low one and in the opossum is 22. At first sight it might appear that the eutherian condition might have arisen from this by tetraploidy. There are two objections, however. In the first place the bulk of the chromatin in marsupials is about the same as in the eutheria, using the sex chromosome as our measure. In the second place, polyploidy could scarcely occur successfully in animals with X-Y sex chromosomes, as most mammals possess, because of the complication occurring in the sex chromosome balance” (Science, April 17, 1925, p. 424). As the X-Y type of sex chromosomes occurs widely not only among vertebrates, but also among insects, nematodes, and echinoderms, Painter’s latter objection excludes evolution by polyploidy from a large portion of the animal kingdom.

Note to [page 90].—

Especially reprehensible, in this respect, are the reconstructions of the Pithecanthropus, the Eoanthropus, and other alleged pitheco-human links modeled by McGregor and others. These imaginative productions, in which cranial fragments are arbitrarily completed and fancifully overlayed with a veneering of human features, have no scientific value or justification. It is consoling, therefore, to note that the great French palæontologist, Marcelin Boule, in his recent book “Les Hommes Fossiles” (Paris, 1921), has entered a timely protest against the appearance of such reconstructions in serious scientific works. “Dubois and Manouvrier,” he says, “have given reconstructions of the skull and even of the head (of the Pithecanthropus). These attempts made by medical men, are much too hypothetical, because we do not possess a single element for the reconstruction of the basis of the brain case, or of the jawbones. We are surprised to see that a great palæontologist, Osborn, publishes efforts of this kind. Dubois proceeded still farther in the realm of imagination when he exhibited at the universal exposition of Paris a plastic and painted reproduction of the Pithecanthropus” (op. cit., p. 105). And elsewhere he remarks: “Some true savants have published portraits, covered with flesh and hair, not only of the Neandertal Man, whose skeleton is known well enough today, but also of the Man of Piltdown, whose remnants are so fragmentary; of the Man of Heidelberg, of whom we have only the lower jawbone; of the Pithecanthropus, of whom there exists only a piece of the cranium and ... two teeth. Such reproductions may have their place in works of the lowest popularization. But they very much deface the books, though otherwise valuable, into which they are introduced.” ... “Men of science—and of conscience—know the difficulties of such attempts too well to regard them as anything more than a pastime” (op. cit., p. 227).

Note to [page 342].—

A fourth possibility is suggested by the case of the so-called skull of the Galley Hill Man, of whose importance as a prehistoric link Sir Arthur Keith held a very high opinion, but which has since turned out to be no skull at all, but merely an odd-shaped piece of stone.

CONTENTS

FOREWORD

The literature on the subject of evolution has already attained such vast dimensions that any attempt to add to it has the appearance of being both superfluous and presumptuous. It is, however, in the fact that the generality of modern works are frankly partisan in their treatment of this theme that the publication of the present work finds justification.

For the philosophers and scientists of the day evolution is evidently something which admits of no debate and which must be maintained at all costs. These thinkers are too intent upon making out a plausible case for the theory to take anything more than the mildest interest in the facts opposed to it. If they advert to them at all, it is always to minimize, and never to accentuate, their antagonistic force. For the moment, at any rate, the minds of scientific writers are closed to unfavorable, and open only to favorable, evidence, so that one must look elsewhere than in their pages for adequate presentation of the case against evolution.

The present work aims at setting forth the side of the question which it is now the fashion to suppress. It refuses to be bound by the convention which prescribes that evolution shall be leniently criticized. It proceeds, in fact, upon the opposite assumption, namely, that a genuinely scientific theory ought not to stand in need of indulgence, but should be able, on the contrary, to endure the acid test of merciless criticism.

Evolution has been termed a “necessary hypothesis.” We have no quarrel with the phrase, provided it really means evolution as an hypothesis, and not evolution as a dogma. For, obviously, the problem of a gradual differentiation of organic species cannot even be investigated upon the fixistic assumption, inasmuch as this assumption destroys the problem at the very outset. Unless we assume the possibility, at least, that modern species of plants and animals may have been the product of a gradual process, there is no problem to investigate. It is, however, a far cry from the possibility to the actuality; and the mere fact that an hypothesis is necessary as an incentive to investigation does not by any means imply that the result of the investigation will be the vindication of its inspirational hypothesis. On the contrary, research often results in the overthrow of the very hypothesis which led to its inception. We can, therefore, quite readily admit the necessity of evolution as an hypothesis, while rejecting its necessity as a dogma.

Assent to evolution as a dogma is advocated not only by materialists, who see in evolutionary cosmogony proof positive of their monism and the complete overthrow of the idea of Creation, but also by certain Catholic scientists, who seem to fear that religion may become involved in the anticipated ruin of fixism. Thus all resistance to the theory of evolution is deprecated by Father Wasmann and Canon Dorlodot on the assumption that the ultimate triumph of this theory is inevitable, and that failure to make provision for this eventuality will lead to just such another blunder as theologians of the sixteenth century made in connection with the Copernican theory. Recollection of the Galileo incident is, doubtless, salutary, in so far as it suggests the wisdom of caution and the imperative necessity of close contact with ascertained facts, but a consideration of this sort is no warrant whatever for an uncritical acceptance of what still remains unverified. History testifies that verification followed close upon the heels of the initial proposal of the heliocentric theory, but the whole trend of scientific discovery has been to destroy, rather than to confirm, all definite formulations of the evolutional theory, in spite of the immense erudition expended in revising them.

There is, in brief, no parity at all between Transformism and the Copernican theory. Among other points of difference, Tuccimei notes especially the following: “The Copernican system,” he remarks, “explains that which is, whereas evolution attempts to explain that which was; it enters, in other words, into the problem of origins, an insoluble problem in the estimation of many illustrious evolutionists, according to whom no experimental verification is possible, given the processes and factors in conjunction with which the theory was proposed. But what is of still greater significance for those who desire to see a parallelism between the two theories is the fact that the Copernican system became, with the discoveries of Newton, a demonstrated thesis, scarcely fifty years after the death of Galileo; the theory of evolution, on the other hand, is at the present day no longer able to hold its own even as an hypothesis, so numerous are its incoherencies and the objections to it raised by its own partisans.” (“La Decadenza di una Teoria,” 1908, p. 11.)

The prospect, then, of a renewal of the Galileo episode is exceedingly remote. Far more imminent to the writer seems the danger that the well-intentioned rescuers of religion may be obliged to perform a most humiliating volte face, after having accepted all too hastily a doctrine favored only for the time being in scientific circles. It is, in fact, by no means inconceivable that the scientific world will eventually discard the now prevalent dogma of evolution. In that case those who have seen fit to reconcile religion with evolution will have the questionable pleasure of unreconciling it in response to this reversal of scientific opinion.

On the whole, the safest attitude toward evolution is the agnostic one. It commits us to no uncertain position. It does not compromise our intellectual sincerity by requiring us to accept the dogmatism of scientific orthodoxy as a substitute for objective evidence. It precludes the possible embarrassment of having to unsay what we formerly said. And last, but not least, it is the attitude of simple truth; for the truest thing that Science is, or ever will be, able to say concerning the problem of organic origins is that she knows nothing about it.

In the present work, we shall endeavor to show that Evolution has long since degenerated into a dogma, which is believed in spite of the facts, and not on account of them. The first three chapters deal with the theory in general, discussing in turn its genetical, morphological, and geological aspects. The last three chapters are devoted to the problem of origins, and treat of the genesis of life, of the human soul, and of the human body, respectively.

While this book is in no sense a work of “popular science,” I have sought to broaden its scope and interest by combining the scientific with the philosophic viewpoint. Certain portions of the text are unavoidably technical, but there is much, besides, that the general reader will be able to follow without difficulty. Students, especially of biology, geology, and experimental psychology, may use it to advantage as supplementary reading in connection with their textbooks.

I wish to acknowledge herewith my indebtedness to the Editor of the Catholic Educational Review, Rev. George Johnson, Ph. D., to whose suggestion and encouragement the inception of this work was largely due. I desire also to express my sincere appreciation of the services rendered in the revision of the manuscript by the Rev. Edward Wenstrup, O.S.B., Professor of Zoölogy, St. Vincent College, Pennsylvania.

BARRY O’TOOLE.

St. Vincent Archabbey,
January 30, 1925.

PART I
EVOLUTION IN GENERAL

CHAPTER I
THE PRESENT CRISIS IN EVOLUTIONARY THOUGHT

Three prominent men, a scientist, a publicist, and an orator, have recently made pronouncements on the theory of Evolution. The trio, of course, to whom allusion is made, are Bateson, Wells, and Bryan. As a result of their utterances, there has been a general reawakening of interest in the problem to which they drew attention. Again and again, in popular as well as scientific publications, men are raising and answering the question: “Is Darwinism dead?” Manifold and various are the answers given, but none of them appears to take the form of an unqualified affirmation or negation. Some reply by drawing a distinction between Darwinism, as a synonym for the theory of evolution in general, and Darwinism, in the sense of the particular form of that theory which had Darwin for its author. Modern research, they assure us, has not affected the former, but has necessitated a revision of ideas with respect to the latter. There are other forms of evolution besides Darwinism, and, as a matter of fact, not Darwin, but Lamarck was the originator of the scientific theory of evolution. Others, though imitating the prudence of the first group in their avoidance of a categorical answer, prefer to reply by means of a distinction based upon their interpretation of the realities of the problem rather than upon any mere terminological consideration.

Of the second group, some, like Osborn, distinguish between the law of evolution and the theoretical explanations of this law proposed by individual scientists. The existence of the law itself, they insist, is not open to question; it is only with respect to hypotheses explanatory of the aforesaid law that doubt and disagreement exist. The obvious objection to such a solution is that, if evolution is really a law of nature, it ought to be reducible to some clear-cut mathematical formula comparable to the formulations of the laws of constant, multiple, and reciprocal proportion in chemistry, or of the laws of segregation, assortment, and linkage in genetics. Assuming, then, that it is a genuine law, how is it that today no one ventures to formulate this evolutional law in definite and quantitative terms?

Others, comprising, perhaps, a majority, prefer to distinguish between the fact and the causes of evolution. Practically all scientists, they aver, agree in accepting evolution as an established fact; it is only with reference to the agencies of evolution that controversy and uncertainty are permissible. To this contention one may justly reply that, by all the canons of linguistic usage, a fact is an observed or experienced event, and that hitherto no one in the past or present has ever been privileged to witness with his senses even so elemental a phenomenon in the evolutionary process as the actual origin of a new and genuine organic species. If, however, the admission be made that the term “fact” is here used in an untechnical sense to denote an inferred event postulated for the purpose of interpreting certain natural phenomena, then the statement that the majority of modern scientists agree as to the “fact” of evolution may be allowed to stand, with no further comment than to note that the formidable number and prestige of the advocates fail to intimidate us. Considerations of this sort are wholly irrelevant, for in science no less than in philosophy authority is worth as much as its arguments and no more.

The limited knowledge of the facts possessed by the biologists of the nineteenth century left their imaginations perilously unfettered and permitted them to indulge in a veritable orgy of theorizing. Now, however, that the trail blazed by the great Augustinian Abbot, Mendel, has been rediscovered, work of real value is being done with the seed pan, the incubator, the microtome, etc., and the wings of irresponsible speculation are clipped. Recent advances in this new field of Mendelian genetics have made it possible to subject to critical examination all that formerly went under the name of “experimental evidence” of evolution. Even with respect to the inferential or circumstantial evidence from palæontology, the enormous deluge of fossils unearthed by the tireless zeal of modern investigators has annihilated, by its sheer complexity, the hasty generalizations and facile simplifications of a generation ago, forcing the adoption of a more critical attitude. Formerly, a graded series of fossil genera sufficed for the construction of a “palæontological pedigree”; now, the worker in this field demands that the chain of descent shall be constructed with species, instead of genera, for links—“Not till we have linked species into lineages, can we group them into genera.” (F. A. Bather, Science, Sept. 17, 1920, p. 264.) This remarkable progress in scientific studies has tended to precipitate the crisis in evolutionary thought, which we propose to consider in the present chapter. Before doing so, however, it will be of advantage to formulate a clear statement of the problem at issue.

Evolution, or transformism, as it is more properly called, may be defined as the theory which regards the present species of plants and animals as modified descendants of earlier forms of life. Nowadays, therefore, the principal use of the term evolution is to denote the developmental theory of organic species. It is, however, a word of many senses. In the eighteenth century, for example, it was employed in a sense at variance with the present usage, that is, to designate the non-developmental theory of embryological encasement or preformation as opposed to the developmental theory of epigenesis. According to the theory of encasement, the adult organism did not arise by the generation of new parts (epigenesis), but by a mere “unfolding” (evolutio) of preëxistent parts. At present, however, evolution is used as a synonym for transformism, though it has other meanings, besides, being sometimes used to signify the formation of inorganic nature as well as the transformation of organic species.

Evolution, in the sense of transformism, is opposed to fixism, the older theory of Linné, according to whom no specific change is possible in plants and animals, all organisms being assumed to have persisted in essential sameness of type from the dawn of organic life down to the present day. The latter theory admits the possibility of environmentally-induced modifications, which are non-germinal and therefore non-inheritable. It also admits the possibility of germinal changes of the varietal, as opposed to the specific, order, but it maintains that all such changes are confined within the limits of the species, and that the boundaries of an organic species are impassable. Transformism, on the contrary, affirms the possibility of specific change, and assumes that the boundaries of organic species have actually been traversed.

What, then, is an organic species? It may be defined as a group of organisms endowed with the hardihood necessary to survive and propagate themselves under natural conditions (i.e. in the wild state), exhibiting a common inheritable type, differing from one another by no major germinal difference, perfectly interfertile with one another, but sexually incompatible with members of an alien specific group, in such wise that they produce hybrids wholly, or partially, sterile, when crossed with organisms outside their own specific group.

David Starr Jordan has wisely called attention to the requisite of viability and survival under natural conditions. “A species,” he says, “is not merely a form or group of individuals distinguished from other groups by definable features. A complete definition involves longevity. A species is a kind of animal or plant which has run the gauntlet of the ages and persisted.... A form is not a species until it has ‘stood.’” (Science, Oct. 20, 1922, p. 448.)

Sexual (gametic) incompatibility as a criterion of specific distinction, presupposes the bisexual or biparental mode of reproduction, namely, syngamy, and is therefore chiefly applicable to the metista, although, if the view tentatively proposed by the protozoölogist, E. A. Minchin, be correct, it would also be applicable to the protista. According to this view, no protist type is a true species, unless it is maintained by syngamy (i.e. bisexual reproduction)—“Not until syngamy was acquired,” says Minchin, “could true species exist among the Protista.” (“An Introduction to the Study of the Protozoa,” p. 141.)

To return, however, to the metista, the horse (Equus caballus) and the ass (Equus asinus) represent two distinct species under a common genus. This is indicated by the fact that the mule, which is the hybrid offspring of their cross, is entirely sterile, producing no offspring whatever, when mated with ass, horse, or mule. Such total sterility, however, is not essential to the proof of specific differentiation; it suffices that the hybrid be less fertile than its parents. As early as 1686, sterility (total or partial) of the hybrid was laid down by John Ray as the fundamental criterion of specific distinction. Hence Bateson complains that Darwinian philosophy flagrantly “ignored the chief attribute of species first pointed out by John Ray that the product of their crosses is frequently sterile in a greater or lesser degree.” (Science, Jan. 20, 1922, p. 58.)

Accordingly, the sameness of type required in members of the same species refers rather to the genotype, that is, the sum-total of internal hereditary factors latent in the germ, than to the phenotype, that is, the expressed somatic characters, viz. the color, structure, size, weight, and all other perceptible properties, in terms of which a given plant or animal is described. Thus it sometimes happens that two distinct species, like the pear-tree and the apple-tree, resemble each other more closely, as regards their external or somatic characters, than two varieties belonging to one and the same species. Nevertheless, the pear-tree and the apple-tree are so unlike in their germinal (genetic) composition that they cannot even be crossed.

According to all theories of transformism, new species arise through the transformation of old species, and hence evolutionists are at one in affirming the occurrence of specific change. When it comes, however, to assigning the agencies or factors, which are supposed to have brought about this transmutation of organic species, there is a wide divergence of opinion. The older systems of transformism, namely, Lamarckism and Darwinism, ascribed the modification of organic species to the operation of the external factors of the environment, while the later school of orthogenesis attributed it to the exclusive operation of factors residing within the organism itself.

Lamarckism, for example, made the formation of organs a response to external conditions imposed by the environment. The elephant, according to this view, being maladjusted to its environment by reason of its clumsy bulk, developed a trunk by using its nose to compensate for its lack of pliancy and agility. Here the use or function precedes the organ and molds the latter to its need. Darwinism agrees with Lamarckism in making the environment the chief arbiter of modification. Its explanation of the elephant’s trunk, however, is negative rather than positive. This animal, it tells us, developed a trunk, because failure to vary in that useful direction would have been penalized by extermination.

Wilson presents, in a very graphic manner, the appalling problem which confronts evolutionists who seek to explain the adaptations of organisms by means of environmental factors. Referring, apparently, to Henderson’s “Fitness of the Environment,” he says: “It has been urged in a recent valuable work ... that fitness is a reciprocal relation, involving the environment no less than the organism. This is both a true and suggestive thought; but does it not leave the naturalist floundering amid the same old quicksands? The historical problem with which he has to deal must be grappled at closer quarters. He is everywhere confronted with specific devices in the organism that must have arisen long after the conditions of environment to which they are adjusted. Animals that live in water are provided with gills. Were this all, we could probably muddle along with the notion that gills are no more than lucky accidents. But we encounter a sticking point in the fact that gills are so often accompanied by a variety of ingenious devices, such as reservoirs, tubes, valves, pumps, strainers, scrubbing brushes, and the like, that are obviously tributary to the main function of breathing. Given water, asks the naturalist, how has all this come into existence and been perfected? The question is an inevitable product of our common sense.” (Smithson. Inst. Rpt. for 1915, p. 405.)

Impressed with the difficulty of accounting for the phenomena of organic adaptation by means of the far too general and unspecific influence of the environment, the orthogenetic school of transformism inaugurated by Nägeli, Eimer, and Kölliker repudiated this explanation, and sought to explain organic evolution on the sole basis of internal factors, such as “directive principles,” or germinal determinants. According to this conception, the elephant first developed his trunk under the drive of some internal agency, and afterwards sought out an environment in which the newly-developed trunk would be useful. In other words, orthogenesis makes the organ precede the function, and is therefore the exact reverse of Lamarckism.

Evolutionists in general, as we have said, regard our present plants and animals as the modified progeny of earlier forms, understanding by “modified” that which is the product of a trans-specific, as distinguished from a varietal or intra-specific, change. To substantiate the claim that changes of specific magnitude have actually taken place, they appeal to two principal kinds of evidence, namely: (a) empirical evidence based on such variations as are now observed to occur among living organisms; (b) inferential evidence, which aposterioristically deduces the common ancestry of allied organic types from their resemblances and their sequence in geological time. Hence, if we omit as negligible certain subsidiary arguments, the whole evidence for organic evolution may be summed up under three heads: (1) the genetic evidence grounded on the facts of variation; (2) the zoölogical evidence based on homology, that is, on structural resemblance together with all further resemblances (physiological and embryological), which such similarity entails; (3) the palæontological evidence which rests on the gradual approximation of fossil types to modern types, when the former are ranged in a series corresponding to the alleged chronological order of their occurrence in the geological strata. It is the bearing of recent genetical research upon the first of these three lines of evidence that we propose to examine in the present chapter, an objective to which a brief and rather eclectic historical survey of evolutionary thought appears to offer the easiest avenue of approach.

While many bizarre speculations on the subject of transformism had been hazarded in centuries prior to the nineteenth, the history of this conception, as a scientific hypothesis, dates from the publication of Lamarck’s “Philosophie Zoologique” in 1809. According to Lamarck, organic species are changed as a result of the indirect influence of the external conditions of life. A change in environment forces a change of habit on the part of the animal. A change in the animal’s habits results in adaptation, that is, in the development or suppression of organs through use or disuse. The adaptation, therefore, thus acquired was not directly imposed by the environment, but only indirectly—that is, through the mediation of habit. Once acquired by the individual animal, however, the adaptation was, so Lamarck thought, taken up by the process of inheritance and perpetuated by being transmitted to the animal’s offspring. The net result would be a progressive differentiation of species due to this indirect influence of a varying environment.

Such was the theory of Lamarck, and it is sound and plausible in all respects save one, namely, the unwarranted assumption that acquired adaptations are inheritable, since these, to quote the words of the Harvard zoölogist, G. H. Parker, “are as a matter of fact just the class of changes in favor of the inheritance of which there is the least evidence.” (“Biology and Social Problems,” 1914, p. 103.)

The next contribution to the philosophy of transformism was made by Charles Darwin, when, in the year 1859, he published his celebrated “Origin of Species.” In this work, the English naturalist bases the evolution of organic species upon the assumed spontaneous tendency of organisms to vary minutely from their normal type in every possible direction. This spontaneous variability gives rise to slight variations, some of which are advantageous, others disadvantageous to the organism. The enormous fecundity of organisms multiplies them in excess of the available food supply, and more, accordingly, are born than can possibly survive. In the ensuing competition or struggle for existence, individuals favorably modified survive and propagate their kind, those unfavorably modified perish without progeny. This process of elimination Darwin termed natural selection. Only individuals favored by it were privileged to propagate their kind, and thus it happened that these minute variations of a useful character were seized upon and perpetuated “by the strong principle of inheritance.” In this way, these slight but useful modifications would tend gradually to accumulate from generation to generation in the direction favored by “natural selection,” until, by the ensuing summation of innumerable minor differences verging in the same direction, a major difference would be produced. The end-result would be a progressive divergence of posterity from the common ancestral type, whence they originally sprang, ending in a multiplicity of new forms or species, all differing to a greater or lesser extent from the primitive type. The contrary hypothesis of a possible convergence of two originally diverse types towards eventual similarity Darwin rejected as an extremely improbable explanation of the observed resemblance of organic forms, which, not without reason, he thought it more credible to ascribe to their assumed divergence from a common ancestral type.

Such was the scheme of evolution elaborated by Charles Darwin. His hypothesis leaves the origin of variations an unsolved mystery. It assumes what has never been proved, namely, the efficacy of “natural selection.” It rests on what has been definitely disproved by factual evidence, namely, the inheritability of the slight variations, now called fluctuations, which, not being transmitted even, by the hereditary process, cannot possibly accumulate from generation to generation, as Darwin imagined. Moreover, fluctuations owe their origin to variability in the external conditions of life (e.g. in temperature, moisture, altitude, exposure, soil, food, etc.), being due to the direct influence or pressure of the environment, and not to any spontaneous tendency within the organism itself. Hence Darwin erred no less with respect to the spontaneity, than with respect to the inheritability and summation, of his “slight variations.”

The subsequent history of Lamarckian and Darwinian Transformism is briefly told. That both should pass into the discard was inevitable, but, thanks to repeated revisions undertaken by loyal adherents, their demise was somewhat retarded. In vain, however, did the Neo-Darwinians attempt to do for Darwinism what the Neo-Lamarckians had as futilely striven to do for Lamarckism. The revisers succeeded only in precipitating a lethal duel between these two rival systems, which has proved disastrous to both. The controversy begun in 1891 between Herbert Spencer and August Weismann marked the climax of this fatal conflict.

Spencer refused to see any value whatever in Darwin’s principle of natural selection, while other Neo-Lamarckians, less extreme, were content to relegate it to the status of a subordinate factor in evolution. Darwin had considered it “the most important means of modification,” but it is safe to say that no modern biologist attaches very much importance to natural selection as a means of accounting for the differences which mark off one species from another. In fact, if natural selection has enjoyed, or still continues to enjoy, any vogue at all, it is not due to its value in natural science (which, for all practical intents and purposes, is nil), but solely to its appeal as “mechanistic solution”; for nothing further is needed to commend it to modern thinkers infected with what Wasmann calls Theophobia. Natural selection, in making the organism a product of the concurrence of blind forces unguided by Divine intelligence, a mere fortuitous result, and not the realization of purpose, has furnished the agnostic with a miserable pretext for omitting God from his attempted explanation of the universe. “Here is the knot,” exclaims Du Bois-Reymond, “here the great difficulty that tortures the intellect which would understand the world. Whoever does not place all activity wholesale under the sway of Epicurean chance, whoever gives only his little finger to teleology, will inevitably arrive at Paley’s discarded ‘Natural Theology,’ and so much the more necessarily, the more clearly he thinks and the more independent his judgment.... The possibility, ever so distant, of banishing from nature its seeming purpose, and putting a blind necessity everywhere in the place of final causes, appears, therefore, as one of the greatest advances in the world of thought, from which a new era will be dated in the treatment of these problems. To have somewhat eased the torture of the intellect which ponders over the world-problem will, as long as philosophical naturalists exist, be Charles Darwin’s greatest title to glory.” (Darwin versus Galiani, “Reden,” Vol. I, p. 211.)

But however indispensable the selection principle may be to a philosophy which proposes to banish the Creator from creation, its scientific insolvency has become so painfully apparent that biologists have lost all confidence in its power to solve the problem of organic origins. It is recognized, for example, that natural selection would suppress, rather than promote, development, seeing that organs have utility only in the state of perfection and are destitute of selection-value while in the imperfect state of transition. Again, the specific differences that diversify the various types of plants and animals are notoriously deficient in selection-value, and therefore the present differentiation of species cannot be accounted for by means of the principle of natural selection. Finally, unless one is prepared to make the preposterous assumption that the environment is a telic mechanism expressly designed for shaping organisms, he is under logical necessity of admitting that the influence of natural selection cannot be anything else than purely destructive. There is, as Wilson points out, no aprioristic ground for supposing that natural selection could do anything more than maintain the status quo, and as for factual proofs of its effectiveness in a positive sense, they are wholly wanting. Professor Caullery of the Sorbonne, in his Harvard lecture of Feb. 24, 1916, assures us that, “since the time of Darwin, natural selection has remained a purely speculative idea and that no one has been able to show its efficacy in concrete indisputable examples.”

Considerations of this sort induced not only Neo-Lamarckians, but many non-partisans as well, to take the field against the Darwinian Selection Principle. Thus Spencer’s caustic attack became a forerunner of others, and eminent biologists, like Fleischmann, Driesch, T. H. Morgan, and Bateson, have in turn poured the vials of their satire upon the attempts of Neo-Darwinians to rehabilitate the philosophy of natural selection. Wm. Bateson warns those, who persist in their credulity with reference to the Darwinian account of organic teleology, that they “will be wise henceforth to base this faith frankly on the impregnable rock of superstition and to abstain from direct appeals to natural fact.” This admonition forms the conclusion of a scathing criticism of what he styles the “fustian of Victorian philosophy.” “In the face of what we know,” it runs, “of the distribution of variability in nature, the scope claimed for natural selection must be greatly reduced. The doctrine of the survival of the fittest is undeniable so long as it is applied to the organism as a whole, but to attempt by this principle to find value in all definiteness of parts and functions, and in the name of science to see fitness everywhere, is mere eighteenth century optimism. Yet it was in its application to the parts, to the details of specific difference, to the spots on the peacock’s tail, to the coloring of an orchid flower, and hosts of such examples, that the potency of natural selection was urged with greatest emphasis. Shorn of these pretensions the doctrine of the survival of favored races is a truism, helping scarcely at all to account for the diversity of species. Tolerance plays almost as considerable a part. By these admissions the last shred of that teleological fustian with which Victorian philosophy loved to clothe the theory of evolution is destroyed.” (Heredity, “Presidential Address to Brit. Ass’n. for Advanc. of Science,” Aug. 14, 1914.) Nor is this all. The Darwinian Selection Principle is reproached with having retarded the progress of science. It is justly accused of having discouraged profound and painstaking analysis by putting into currency its shallow and spurious solution of biological problems. “Too often in the past,” says Edmund Wilson, “the facile formulas of natural selection have been made use of to carry us lightly over the surface of unsuspected depths that would have richly repaid serious exploration.” (Smithson. Inst. Rpt. for 1915, p. 406.)

In retaliation for the destructive criticism of natural selection, the Neo-Darwinians have proceeded to pulverize the Lamarckian tenet concerning the inheritability of acquired adaptations. Weismann, having laid down his classic distinction between the soma (comprising the vegetative or tissue cells in contact with the environment) and the germ (i.e. the sequestered reproductive cells or gametes, which are sheltered from environmental vicissitudes), showed that the Lamarckian assumption that a change in the somatic cells (which constitute the organism of the individual) is registered in the germ cells (which constitute the vehicle of racial inheritance), is supported neither by a priori probability nor by any facts of observation. Germ cells give rise by division to somatic or tissue cells, but the converse is not true; for, once a cell has become differentiated and specialized into a tissue cell, it can never again give rise by division to germ cells, but only to other tissue cells of its own kind. Hence the possibility of a change in the tissue being transmitted to the germ has no antecedent probability in its favor. Neither is it grounded on the facts of observation. Bodily mutilations of the parent are not transmitted to the offspring. The child of a blacksmith is not born with a more developed right arm than that of a tailor’s child. When the ovaries from a white rabbit are grafted into a black rabbit, whose own ovaries have been previously removed, the latter, if mated to a white male, will produce spotlessly white young. Hence the offspring inherit the characters of the germ track of the white female, whence the ovaries were derived, without being influenced in the least by the pigmented somatic cells of the nurse-body (i.e. the black female), into which the ovaries were grafted. Kammerer’s experiments, in which young salamanders were found to exhibit at birth the coloration, which their parents had acquired through the action of sunlight, fail to convince, because, in this case, the bodies of the parents are not sufficiently impervious to light to preclude its direct action upon the gametes while in the reproductive organs of the parents. Hence we cannot be sure but that the coloration of the offspring derived from these gametes is due to the direct agency of sunlight rather than to the intermediate influence of the modified somatic cells upon the germ plasm.

The same objection holds true of the recent experiments, in which the germ cells have been modified by modifying the interior medium or internal environment by means of antibodies and hormones. No one doubts the possibility of influencing heredity by a direct modification of the germ cells, especially when, as is always the case in these experiments, the modification produced is destructive rather than constructive. The experiments, therefore, of Prof. M. F. Guyer of Wisconsin University, in which a germinally-transmitted eye defect was produced by injecting pregnant female rabbits with an antilens serum derived from fowls immunized to the crystalline lens of rabbits as antigen, are beside the mark. To demonstrate the Lamarckian thesis one must furnish evidence of a constructive addition to inheritance by means of prior somatic acquisition. The transmission of defects artificially produced is not so much a process of inheritance (transmission of type) as rather one of degeneracy (failure to equate the parental type).[1] Commenting on Guyer’s suggestion that an organism capable of producing antibodies that are germinally-destructive, may also be able to produce constructive bodies, Prof. Edwin S. Goodrich says: “The real weakness of the theory is that it does not escape from the fundamental objections we have already put forward as fatal to Lamarckism. If an effect has been produced, either the supposed constructive substance was present from the first, as an ordinary internal environmental condition necessary for the normal development of the character, or it must have been introduced from without by the application of a new stimulus. The same objection does not apply to the destructive effect. No one doubts that if a factor could be destroyed by a hot needle or picked out with a fine forceps the effect of the operation would persist throughout subsequent generations.” (Science, Dec. 2, 1921, p. 535.)

But in demonstrating against the Neo-Lamarckians that somatic modifications unrepresented in the germ plasm could have no significance in the process of racial evolution, Weismann had proved too much. His argument was no less telling against Darwinism than it was against Lamarckism. Darwin’s “individual differences” or “slight variations,” now spoken of as fluctuations, were quite as unrepresented and unrecorded in the germ cells as Lamarck’s “acquired adaptations.” There can be no “summation of individual differences” for the simple reason that fluctuations have no germinal basis and are therefore uninheritable—“We must bear in mind the fact,” says Prof. Edmund Wilson, “that Darwin often failed to distinguish between non-inheritable fluctuations and hereditary mutations of small degree.” (Smithson. Inst. Rpt. for 1915, p. 406.) Fluctuations, as we have seen, are due to variability in the environmental conditions, e.g. in access to soil nutrients, etc. As an instance of fluctuational variation the seeds of the ragweed may be cited. Normally these seeds have six spines, but around this average there is considerable fluctuation in individual seeds, some having as many as nine spines and others no more than one. Yet the plants reared from nine-spine seeds, even when similarly mated, show no greater tendency to produce nine-spine seeds than do plants reared from one-spine seeds.

To meet the difficulty presented by the non-inheritability of the Lamarckian adaptation and the Darwinian fluctuation, De Vries substituted for them those rare and abruptly-appearing inheritable variations, which he called mutations[2] and regarded as elementary steps in the evolutionary process. This new version of transformism was announced by De Vries in 1901, and more fully explained in his “Die Mutations-Theorie” (Leipzig, 1902-1903). Renner has shown that De Vries’ new forms of Œnothera were cases of complex hybridization rather than real mutants, as the forms produced by mutation are now called. Nevertheless, the work of Morgan, Bateson, and others leaves little doubt as to the actual occurrence of factorial mutants, while Dr. Albert F. Blakeslee has demonstrated the existence of chromosomal mutants. When unqualified, the term mutant usually denotes the factorial mutant, which arises from a change in one or more of the concatenated genes (hereditary factors) of a single chromosome (nuclear thread) in the germinal (i.e. gametic) complex. All such changes are called factorial mutations. They are hereditarily transmissible, and affect the somatic characters of the race permanently, although, in rare cases, such as that of the bar-eyed Drosophila mutant, the phenomenon of reversion has been observed. The chromosomal mutant, on the contrary, is not due to changes in the single factors or genes, but to duplication of one or more entire chromosomes (linkage-groups) in the gametic complex. Like the factorial mutant, it produces a permanent and heritable modification. The increase in nuclear material involved in chromosomal mutation (i.e. duplication) seems to cause a proportionate increase in the cytoplasmic mass of the single somatic cells, which manifests itself in the phenotype as giantism. De Vries’ Œnothera gigas is a chromosomal mutant illustrative of this phenomenon. Besides the foregoing, there is the pseudomutant produced by the factorial recombination, which results from a crossover, i.e. an exchange of genes or factors between two germinal chromosomes of the same synaptic pair. This reciprocal transfer of genes from one homologous chromosome to another happens, in a certain percentage of cases, during synapsis. The percentage can be artificially increased by exposing young female hybrids to special conditions of temperature.

If these new mutant forms could be regarded as genuine new species, then the fact that such variations are heritable and come within the range of actual observation, would constitute the long-sought empirical proof of the reality of evolution. Consciously or subconsciously, however, De Vries recognized that this was not the case; for he refers to mutants as “elementary species,” and does not venture to present them as authentic organic species.

The factorial mutant answers neither the endurance test nor the intersterility test of a genuine species. It would, doubtless, be going too far to regard all such mutant forms as examples of germinal degeneracy, but it cannot be denied that all of them, when compared to the wild type, are in the direction of unfitness, none of them being viable and prosperous under the severe conditions obtaining in the wild state. Bateson, who seems to regard all mutant characters as recessive and due to germinal loss, declares: “Even in Drosophila, where hundreds of genetically distinct factors have been identified, very few new dominants, that is to say positive additions, have been seen, and I am assured that none of them are of a class which could be expected to be viable under natural conditions. I understand even that none are certainly viable in the homozygous state.” (Toronto Address, Science, Jan. 20, 1922, p. 59.) “Garden or greenhouse products,” says D. S. Jordan, “are immensely interesting and instructive, but they throw little light on the origin of species. To call them species is like calling dress-parade cadets ‘soldiers.’ I have heard this definition of a soldier, ‘one that has stood.’ It is easy to trick out a group of boys to look like soldiers, but you can not define them as such until they have ‘stood.’” (Science, Oct. 20, 1922.) In a word, factorial mutants, owing, as they do, their survival exclusively to the protection of artificial conditions, could never become the hardy pioneers of new species.

Bateson insists that the mutational variation represents a change of loss. “Almost all that we have seen,” he says, “are variations in which we recognize that elements have been lost.” (Science, Jan. 20, 1922, p. 59.) In his Address to the British Association (1914), he cites numerous examples tending to show that mutant characters are but diminutions or intensifications of characters pre-existent in the wild or normal stock, all of which are explicable as effects of the loss (total or partial) of either positive, or inhibitive (epistatic) hereditary factors (genes). One of these instances illustrating the subtractive nature of the factorial mutation is that of the Primula “Coral King,” a salmon-colored mutant, which was suddenly given off by a red variety of Primula called “Crimson King.” Such a mutation is obviously based on the loss of a germinal factor for color. The loss, however, is sometimes partial rather than total, as instanced in the case of the purple-edged Picotee sweet pea, which arose from the wholly purple wild variety by fractionation of the genetic factor for purple pigment. Even where the mutational variation appears to be one of gain, as happens when a positive character appears de novo in the phenotype, or when a dilute parental character is intensified in the offspring, it is, nevertheless, interpretable as a result of germinal loss, the loss, namely, total or partial, of a genetic inhibitor. Such inhibitive genes or factors are known to exist. Bateson has shown, for example, that the whiteness of White Leghorn chickens is due, not to the absence of color-factors, but to the presence of a genetic inhibitor—“The white of White Leghorns,” he says, “is not, as white in nature often is, due to the loss of the color elements, but to the action of something which inhibits their expression.” (Address to the Brit. Ass’n., Smithson. Inst. Rpt. for 1915, p. 368.) Thus the sudden appearance in the offspring of a character not visibly represented in the parents may be due, not to germinal acquisition, but the loss of an inhibitory gene, whose elimination allows the somatic character previously suppressed by it to appear. Hence Bateson concludes: “In spite of seeming perversity, therefore, we have to admit that there is no evolutionary change which in the present state of our knowledge we can positively declare to be not due to loss.” (Loc. cit., p. 375.)

Another consideration, which disqualifies the factorial mutant for the rôle of a new species, is its failure to pass the test of interspecific sterility. When individuals from two distinct species are crossed, the offspring of the cross is either completely sterile, as instanced in the mule, or at least partially so. But when, for example, the sepia-eyed mutant of the vinegar fly is back-crossed with the red-eyed wild type, whence it originally sprang, the product of the cross is a red-eyed hybrid, which is perfectly fertile with other sepia-wild hybrids, with wild flies, and with sepia mutants. This proves that the sepia-eyed mutant has departed, so to speak, only a varietal, and not a specific, distance away from the parent stock. Ordinary or factorial mutation does not, therefore, as De Vries imagined, produce new species. These mutants do, indeed, meet the requirement of permanent transmissibility, for their distinctive characters cannot be obliterated by any amount of crossing. Nevertheless, the factorial mutation falls short of being an empirical proof of evolution, because it is a varietal, and not a specific, change. In other words, factorial mutants are new varieties and not new species. Only a heritable change based on germinal acquisition of sufficient magnitude to produce gametic incompatibility between the variant and the parent type would constitute direct evidence of the transmutation of species, provided, of course, that the variant were also capable of survival under the natural conditions of the wild state.

In his Toronto address of December 28, 1921, Wm. Bateson announced the failure of De Vries’ Mutation Theory, when he said: “But that particular and essential bit of the theory of evolution, which is concerned with the origin and nature of species remains utterly mysterious. We no longer feel as we used to do, that the process of variation, now contemporaneously occurring, is the beginning of a work which needs merely the element of time for its completion; for even time cannot complete that which has not yet begun. The conclusion in which we were brought up that species are a product of a summation of variations ignored the chief attribute of species first pointed out by John Ray that the product of their crosses is frequently sterile in greater or less degree. Huxley, very early in the debate, pointed out this grave defect in the evidence, but before breeding researches had been made on a large scale no one felt the objection to be serious. Extended work might be trusted to supply the deficiency. It has not done so, and the significance of the negative evidence can no longer be denied....

“If species have a common origin where did they pick up the ingredients which produce this sexual incompatibility? Almost certainly it is a variation in which something has been added. We have come to see that variations can very commonly—I do not say always—be distinguished as positive and negative.... Now we have no difficulty in finding evidence of variation by loss, but variations by addition are rarities, even if there are any such which must be so accounted. The variations to which interspecific sterility is due are obviously variations in which something is apparently added to the stock of ingredients. It is one of the common experiences of the breeder that when a hybrid is partially sterile, and from it any fertile offspring can be obtained, the sterility, once lost, disappears. This has been the history of many, perhaps most, of our cultivated plants of hybrid origin.

“The production of an indubitably sterile hybrid from completely fertile parents which has arisen under critical observation is the event for which we wait. Until this event is witnessed, our knowledge of evolution is incomplete in a vital respect. From time to time such an observation is published, but none has yet survived criticism.” (Science, Jan. 20, 1922, pp. 58, 59.)

But what of the chromosomal mutant? For our knowledge of this type of mutation we are largely indebted to Blakeslee’s researches and experiments on the Jimson weed (Datura stramonium). According to Blakeslee, chromosomal mutants result from duplication, or from reduction, of the chromosomes, and they are classified as balanced or unbalanced types according as all, or only some, of the chromosomal linkage-groups are similarly doubled or reduced. If only one of the homologous chromosomes of a synaptic pair is doubled, the mutant is termed a triploid form. It is balanced when one homologous chromosome is doubled in every synaptic pair, but if one or more chromosomes be added to, or subtracted from, this balanced triploid complex, the mutant is termed an unbalanced triploid. When all the chromosomes of the normal diploid complex are uniformly doubled, we have a balanced tetraploid race. The subtraction or addition of one or more chromosomes in the case of a balanced tetraploid complex renders it an unbalanced tetraploid mutant. The retention in somatic cells of the haploid number of chromosomes characteristic of gametes and gametophytes gives a balanced haploid mutant, from which hitherto no unbalanced haploids have been obtained. The normal diploid type and the balanced tetraploid type are said to constitute an even balance, while balanced triploids and haploids constitute an odd balance. The odd balances and all the unbalanced mutants are largely sterile. Thus, for example, more than 80% of the pollen of the haploid mutant is bad. “The normal Jimson Weed,” says Blakeslee, “is diploid (2n) with a total of 24 chromosomes in somatic cells. In previous papers the finding of tetraploids (4n) with 48 chromosomes and triploids (3n) with 36 was reported, as well as unbalanced mutants with 25 chromosomes represented by the formula (2n + 1). The finding of two haploid or 1n plants, which we are now able to report, adds a new chromosomal type to the balanced series of mutants in Datura. This series now stands: 1n, 2n, 3n, 4n. Since a series of unbalanced mutants has been obtained from each of the other balanced types by the addition or subtraction of one or more chromosomes, it is possible that a similar series of unbalanced mutants may be obtainable from our new haploid plants, despite the great unbalance which would thereby result.” (Science, June 16, 1923, p. 646.) The haploid mutant, of which Blakeslee speaks, has, of course, 12 unpaired chromosomes in its somatic cells.

The balanced triploid is, like the haploid mutant, largely sterile, and is only obtainable by crossing the tetraploid race with the normal diploid plant. Since, then, the product of the cross of the diploid and tetraploid races is sterile, the tetraploid race fulfills the sterility test of a distinct species. Whether or not it fulfills the endurance test of survival under natural condition is doubtful, inasmuch as diploid Daturas are about three times as prolific as the tetraploid race. Moreover, as Blakeslee himself confessed in a lecture at Woods Hole attended by the present writer in the summer of 1923, the origin of a balanced tetraploid form from the normal diploid type by simultaneous duplication of all the chromosomes in the diploid complex, is an event that has yet to be witnessed. Nor is any gradual transition from the diploid to the tetraploid race, by way of unbalanced types and triploids, conceivable, seeing that such forms are too sterile to maintain themselves, and are, in fact, incapable of transmitting their own type in the absence of artificial intervention. There are, it is true, some instances, in which diploid and tetraploid races and species occur together in cultivation and in nature. In certain cases, this tetraploidy is merely apparent, being due to fragmentation of the chromosomes; in other cases, it is really due to chromosomal duplication, giving rise to genuine tetraploid forms. The question is often hard to decide, the mere number of the chromosomes being not, in itself, a safe criterion. Of the actual origin, however, of tetraploid from diploid races we have as yet no observational evidence. Hence Blakeslee’s researches on the chromosomal mutant have so far failed to furnish experimental proof of the origin of a genuine new species. Besides, waiving all other considerations, the limits within which chromosomal duplication is possible are of necessity so narrow, that, at best, this phenomenon can only be invoked to explain a very small range of variation. In fact, it is doubtful whether haploidy, triploidy, and tetraploidy have any important bearing whatever upon the problem of the origin of species. (See [Addenda].)

The mutation, then, in so far as we have experimental knowledge of it, does not fulfill requirements of a specific change. It cannot even be regarded as an elementary step in the direction of such a change. With this admission, De-Vriesianism becomes obsolete, descending like its predecessors, Lamarckism and Darwinism, into the charnel-house of discarded systems whose value is historic, but no longer scientific. When we enquire into the reason of this common demise of all the classic systems of transformism, we find it to reside in the progress of the new science of Mendelian genetics, whose foundations were laid by an Augustinian monk of the nineteenth century. Six years after the appearance of Darwin’s “Origin of Species,” Gregor Johann Mendel published a short paper entitled “Versuche über Pflanzen-hybriden,” which, unnoticed at the time by a scientific world preoccupied with Darwinian fantasies, was destined, on its coming to light at the beginning of the present century, to administer the final coup de grace to all the elaborate schemes of evolution that had preceded or followed its initial publication. It took half a century, however, before the dust of Darwinian sensationalism subsided sufficiently, to permit the “rediscovery” of Mendel’s solid and genuine contribution to biological science. But the Prälat of the abbey at Brünn never lived to see the day of his triumph. The true genius of his century, he died unhonored and unsung, a pretender being crowned in his stead. For Coulter says of Darwin: “He died April 19, 1882, probably the most honored scientific man in the world.” (Evolution, 1916, p. 35.)

Within the small dimensions of the paper, of which we have spoken, Mendel had compressed the results of years of carefully conceived and accurately executed experimentation reduced to precise statistical form and interpreted with a penetrating sagacity of the highest order. It is no exaggeration to say that his discovery has revolutionized the science of biology, giving it, for the first time, mathematical formulas comparable to those of chemistry. His two laws of inheritance, namely, the law of segregation and the law of independent assortment of characters, have, as previously intimated, become the basis of the new science of Genetics. His analysis of biparental reproduction has interpreted for us the cytological phenomena of synapsis, meiosis, and syngamy, has explained for us the instability of hybrids, has placed Weismann’s speculations concerning the autonomy and continuity of the germ plasm on a firm basis of experimental fact, has clarified all our notions respecting the mode and range of hereditary transmission, and has, in a word, opened our eyes to that new and hitherto unexplored realm of nature which Bateson calls “the world of gametes.”

Efforts have been made to construct systems of transformism along Mendelian lines, but none of them has met with notable success. Lotsy, for example, sought to explain all variation on the basis of the rearrangement of preëxistent genetic factors brought about by crossing. But such a solution of the problem is very unsatisfactory. In the first place, the generality of hybrid (heterozygous) forms are ruled out on the score of instability. The phenotype of hybrids is directly dependent, not on the genes themselves, but on the diploid combination of genes contained in the zygote. This combination, however, is always dissolved in the process of gamete-formation, by the segregative reduction division which occurs in the reproductive organs of the hybrid. Hybrids, therefore, do not breed true, if propagated by sexual reproduction. To maintain constancy of type in hybrids, one must resort to somatogenic reproduction (i.e. vegetative growth from stems, etc.). Certain violets, in fact, as well as blackberries, are maintained in a state of constant hybridism by means of this sort of reproduction, even in nature. In the case of balanced lethals (i.e. factors causing death in the pure or homozygous state), the hybrid phenotype may be maintained even by sexual reproduction, inasmuch as all the pure (homozygous) offspring are non-viable. Two lethals are said to be balanced, when they occur, the first in one and the second in the other homologous chromosome of the same synaptic pair. “Such a factorial situation would maintain a state of constant heterozygosis, the fixed hybridism of an impure species ... the hybrid will breed true until the relative position of the lethals are changed by a crossover, or the genetical constitution in these respects is altered by a mutation.” (Davis, Science, Feb. 3, 1922, p. 111.) As is evident, however, the condition of balanced lethals involves a considerable reduction in fertility.

Hybridization, moreover, is successful between varieties of the same species rather than between distinct species. Interspecific crosses are in some cases entirely unproductive, in other cases productive of wholly-sterile, hybrids, and in still other cases productive of semisterile hybrids. When semisterile hybrids are obtainable from an interspecific cross, the phenotype can be kept constant by somatogenic reproduction, but, as we shall see in a later chapter, this kind of reproduction does not counteract senescence, and stock thus propagated usually plays out within a determinate period. Finally, the mixture of incompatible germinal elements involved in an interspecific cross tends to produce forms, which are subnormal in their viability and vitality. The conclusions of Goodspeed and Clausen are the following: “(1) As a consequence of modern Mendelian developments, the Mendelian factors may be considered as making up a reaction system, the elements of which exhibit more or less specific relations to one another; (2) strictly Mendelian results are to be expected only when the contrast is between factor differences within a common Mendelian reaction system as is ordinarily the case in varietal hybrids; (3) when distinct reaction systems are involved, as in species crosses, the phenomena must be viewed in the light of a contrast between systems rather than between specific factor differences, and the results will depend upon the degree of mutual compatibility displayed between the specific elements of the two systems.” (Amer. Nat., 51 (1917), p. 99.) To these conclusions may be added the pertinent observation of Bradley Moore Davis: “Of particular import,” he says, “is the expectation that lethals most frequently owe their presence to the heterozygous condition since the mixing of diverse germ plasms seems likely to lead to the breaking down of delicate and vital adjustments in proportion relative to the degree of protoplasmic confusion, and this means chemical and physical disturbance.” (Science, Feb. 3, 1923, p. 111.)

But crossing produces, in the second filial generation (F₂), pure (homozygous) as well as hybrid (heterozygous) forms.⅖ In some cases these pure forms are new, the phenotype being different from that of either pure grandparent. Such a result is produced by random assortment of the chromosomes in gamete and zygote formation, and occurs when the genes for two or more pairs of contrasted characters are located in different chromosome pairs. The phenomenon is formulated in Mendel’s Second Law, the law of independent assortment. The novelty, however, of the true-breeding forms thus produced is not absolute, but relative. There is no origination of new hereditary factors. It is simply a recombination of the old genes of different stocks, the genes themselves undergoing no intrinsic alteration. The combination is new, but not the elements combined. In addition to chromosomal recombination, we have factorial recombination by means of crossovers. This, too, can produce new and true-breeding forms of a fixed nature, but here, likewise, it is the combination, and not the elements combined, which is new. The “new” forms thus produced are called, as we have seen, pseudomutants. When pseudomutations, that is, crossovers, occur in conjunction with the condition of balanced lethals, they closely simulate genuine factorial mutations. This is exemplified in the case of De Vries’ Œnothera Lamarckiana, which is the product of a crossover supervening upon a situation of balanced lethals. In cases of this kind, the crossover releases hitherto suppressed recessive characters, giving the appearance of real mutation. “The workers with Drosophila,” says Davis, “seem inclined to believe that much of the phenomena simulating mutation in their material is in reality the appearance of characters set free by the breaking of lethal adjustments which held the characters latent. Well-known workers have arrived at similar conclusions for Œnothera material and are not content to accept as evidence of mutations the behavior of Lamarckiana and some other forms when they throw their marked variants.” (Science, Feb. 3, 1922, p. 111.)

The new forms, however, resulting from random assortment and crossovers cannot be regarded as new species. “Analysis,” says Bateson, “has revealed hosts of transferable characters. Their combinations suffice to supply in abundance series of types which might pass for new species, and certainly would be so classed if they were met with in nature. Yet critically tested, we find that they are not distinct species and we have no reason to suppose any accumulation of characters of the same order would culminate in the production of distinct species. Specific difference therefore must be regarded as probably attaching to the base upon which these transferables are implanted, of which we know absolutely nothing at all. Nothing that we have witnessed in the contemporary world can colorably be interpreted as providing the sort of evidence required.” (Science, Jan. 20, 1922, pp. 59, 60.)

Anyone thoroughly acquainted with the results of genetical analysis and research will find it impossible to escape the conviction that there is no such thing as experimental evidence for evolution. In spite of the enormous advances made in the fields of genetics and cytology, the problem of the origin of species is, scientifically speaking, as mysterious as ever. No variation of which we have experience is interpretable as the transmutation of a specific type, and David Starr Jordan voices an inevitable conclusion when he says: “None of the created ‘new species’ of plant or animal I know of would last five years in the open, nor is there the slightest evidence that any new species of field or forest or ocean ever originated from mutation, discontinuous variation, or hybridization.” (Science, Oct. 20, 1922, p. 448.)

“In any case,” as Professor Caullery tells us in his Harvard lecture on the “Problem of Evolution,” “we do not see in the facts emerging from Mendelism, how evolution, in the sense that morphology suggests, can have come about. And it comes to pass that some of the biologists of greatest authority in the study of Mendelian heredity are led, with regard to evolution, either to a more or less complete agnosticism, or to the expression of ideas quite opposed to those of the preceding generation; ideas which would almost take us back to creationism.” (Smithson. Inst. Rpt. for 1916, p. 334.) It is, of course, impossible within the limits of a single chapter to convey any adequate impression of all that Mendel’s epoch-making achievement portends, but what has been said is sufficient to give some idea of the acuteness of the crisis through which the theory of organic evolution is passing as a result of his discovery. In its classic forms of Lamarckism, Darwinism and De-Vriesianism, the survival of the theory is out of the question. Whether or not it can be rehabilitated in any form whatever is a matter open to doubt. Transfixed by the innumerable spears of modern objections, its extremity calls to mind the plight of the Lion of Lucerne. Possibly, it is destined to find a rescuer in some great genius of the future, but of one thing, at least, we may be perfectly certain, namely, that, even if rejuvenated, it will never again resume the lineaments traced by Charles Darwin. In the face of this certainty, it is almost pitiful to hear the die-hards of Darwinism bolstering up a lost cause with the wretched quibble that, though natural selection has been discredited as an explanation of the differentiation of species, Darwinism “in its essentials” survives intact. For, if there is any feature which, beyond all else, deserves to be called an essential of Darwin’s system, surely it is natural selection. For Darwin it was “the most important” agency of transformation (cf. “Origin of Species,” 6th ed., p. 5). Apart from his hypothesis of the summation through inheritance of slight variations (“fluctuations”), now completely demolished by the new science of genetics, it represented his sole contribution to the philosophy of transformism. It alone distinguishes Darwinism from Lamarckism, its prototype. Without it the “Origin of Species” would be Hamlet without the Prince of Denmark. With it Darwin’s fame should stand or fall. Therefore, since Darwin erred in making it “the most important means of modification,” Darwinism is dead, and no grief of mourners can resuscitate the corpse. “Through the last fifty years,” says Bateson, “this theme of the natural selection of favored races has been developed and expounded in writings innumerable. Favored races certainly can replace others. The argument is sound, but we are doubtful of its value. For us that debate stands adjourned. We go to Darwin for his incomparable collection of facts. We would fain emulate his scholarship, his width, and his power of exposition, but to us he speaks no more with philosophical authority. We read his scheme of evolution as we would those of Lucretius or of Lamarck, delighting in their simplicity and their courage.” (Heredity, Presid. Add. to British Assoc. for Advanc. of Science, Smith. Inst. Rpt. for 1915, p. 365.)

CHAPTER II
HOMOLOGY AND ITS EVOLUTIONARY INTERPRETATION

The recent revival of interest in the problem of evolution seems to have called forth two very opposite expressions of opinion from those who profess to represent Catholic thought on this subject. M. Henri de Dorlodot, in his “Le Darwinisme,” appears in the rôle of an ardent admirer of Darwin and an enthusiastic advocate of the doctrine of Transformism. The contrary attitude is adopted by Mr. Alfred McCann, whose “God—or Gorilla” is bitterly antagonistic not only to Darwinism but to any form whatever of the theory of Transformism. Both of these works possess merits which it would be unjust to overlook. Dorlodot deserves credit for having shown conclusively that there is absolutely nothing in the Scriptures, or in Patristic tradition, or in Catholic theology, or in the philosophy of the Schools, which conflicts with our acceptance of organic evolution as an hypothesis explanatory of certain biological facts. In like manner, it must be acknowledged that, even after a liberal discount has been made in penalty of its bias and scientific inaccuracy, Mr. McCann’s book still contains a formidable residue of serious objections, which the friends of evolution will probably find it more convenient to sidestep than to answer.

Unfortunately, however, neither of these writers maintains that balanced mental poise which one likes to see in the defenders of Catholic truth. Dorlodot seems too profoundly impressed with the desirability of occupying a popular position to do impartial justice to the problem at issue, and his anxiety to keep in step with the majority blinds him apparently to the flaws of that “Darwinism” which he praises. Had he been content with a simple demarcation of negative limits, there would be no ground for complaint. But, when he goes so far as to bestow unmerited praise upon the author of the mechanistic “Origin of Species” and the materialistic “Descent of Man”; when, by confounding Darwinism with evolution, he consents to that historical injustice which allows Darwin to play Jacob to Lamarck’s Esau, and which leaves the original genius of Mendel in obscurity while it accords the limelight of fame to the unoriginal expounder of a borrowed conception; when, by means of the sophistry of anachronism, he speciously endeavors to bring the speculations of an Augustine or an Aquinas into alignment with those of the ex-divinity student of Cambridge; when he assumes that Fixism is so evidently wrong that its claims are unworthy of consideration, whereas Transformism is so evidently right that we can dispense with the formality of examining its credentials; when, in a word, he expresses himself not merely in the sense, but in the very stereotyped cant phrases of a dead philosophy, we realize, with regret, that his conclusions are based, not on any reasoned analysis of the evidence, but solely upon the dogmatism of scientific orthodoxy, that his thought is cast in antiquated molds, and that for him, apparently, the sixty-five years of discovery and disillusionment, which have intervened since the publication of the “Origin of Species,” have passed in vain.

But, if Dorlodot represents the extreme of uncritical approval, Mr. McCann represents the opposite, and no less reprehensible, extreme of biased antagonism, that is neither fair in method nor conciliatory in tone. Instead of adhering to the time-honored practice of Catholic controversialists, which is rather to overstate than to understate the argument of an adversary, Mr. McCann tends, at times, to minimize, in his restatement, the force of an opponent’s reasoning. He frequently belittles with mere flippant sneer, and is only too ready to question the good faith of those who do not share his convictions. Thus, when McCann ridicules Wells and accuses him of pure romancing, because the latter speaks of certain hairy “wild women” of the Caves, he himself seems to be ignorant of the fact that a palæolithic etching has been found representing a woman so covered with hair that she had no need of other apparel (the bas-relief from Laugerie-Basse carved on reindeer palm—cf. Smithson. Inst. Rpt. for 1909, p. 540 and Plate 2).

Mr. McCann may object, with truth, that this is far from being a proof that the primitive representatives of the human race were hairy individuals, but the fact suffices, at least, to acquit Mr. Wells of the charge of unscrupulous invention. Hence, while we have no wish to excuse the lamentable lack of scientific conscientiousness so manifestly apparent in the writings of popularizers of evolution, like Wells, Osborn, and Haeckel, nevertheless common justice, not to speak of charity, constrains us to presume that, occasionally at least, their departures from the norm of objective fact were due to ordinary human fallibility or to the mental blindness induced by preconceptions, rather than to any deliberate intent to deceive. And we feel ourselves impelled to make this allowance for unconscious inaccuracy all the more readily that we are confronted with the necessity of extending the selfsame indulgence to Mr. McCann himself. Thus we find that the seventh illustration in “God—or Gorilla” (opposite p. 56) bears the legend: “Skeletons of man and chimpanzee compared,” when, in point of fact, the ape skeleton in question is not that of a chimpanzee (Troglodytes niger) at all, but of an Orang-utan (Simia satyrus), as the reader may verify for himself by consulting Plate VI of the English version of Wasmann’s “Modern Biology,” where the identical illustration appears above its proper title: “Skeleton of an adult Orang-utan.” Since the error is repeated in the index of illustrations and in the legend of the third illustration of the appendix, it is impossible, in this instance, to shift the responsibility from Mr. McCann to the printer. In any case, it is sincerely to be hoped that this, and several other infelicitous errors will be rectified in the next edition of “God—or Gorilla.”

In the next chapter we shall have occasion to refer again to Dorlodot’s book. For the present, however, his work need not concern us, while in that of Mr. McCann we single out but one point as germane to our subject, namely, the latter’s inadequate rebuttal of the evolutionary argument from homology. The futility of his method, which consists in matching insignificant differences against preponderant resemblances, and in exclaiming with ironic incredulity: “Note extraordinary resemblances!” becomes painfully evident, so soon as proper presentation enables us to appreciate the true force of the argument he is striving to refute. Functionally the foot of a Troglodyte ape may be a “hand,” but structurally it is the homologue of the human foot, and not of the human hand; nor is this homology effectually disposed of by stressing the dissimilarity of the hallux, whilst one remains discreetly reticent concerning the similarity of the calcaneum. For two reasons, therefore, the irrelevance of Mr. McCann’s reply is of special interest here: (1) because it illustrates concretely the danger of rendering a refutation inconsequential and inept by failing to plumb the full depth of the difficulty one is seeking to solve; (2) because it shows that it is vain to attempt to remove man’s body from the scope of this argument by citing the inconsiderable structural differences which distinguish him from the ape, so that, unless the argument from homology proves upon closer scrutiny to be inherently inconclusive, its applicability to the human body is a foregone conclusion, and implies with irresistible logic the common ancestry of men and apes.

Such are the reflections suggested by the meager measure of justice which Mr. McCann accords to the strongest zoölogical evidence in favor of evolution, and they contain in germ a feasible program for the present chapter, which, accordingly, will address itself: first, to the task of ascertaining the true significance of homology in the abstract as well as the full extent of its application in the concrete; second, to that of determining with critical precision its intrinsic value as an argument for the theory of transmutation.

Homology is a technical term used by the systematists of botany, zoölogy and comparative anatomy to signify basic structural similarity as distinguished from superficial functional similarity, the latter being termed analogy. Organisms are said to exemplify the phenomenon of homology when, beneath a certain amount of external diversity, they possess in common a group of correlated internal resemblances of such a nature that the organisms possessing them appear to be constructed upon the same fundamental plan. In cases of this kind, the basic similarity is frequently masked by a veneer of unlikeness, and it is only below this shallow surface of divergence that we find evidences of the identical structure or common type.

Thus organs of different animals are said to be homologous when they are composed of like parts arranged in similar relation to one another. Homologous organs correspond bone for bone and tissue for tissue, so that each component of the one finds its respective counterpart in the other. The organs in question may be functionally specialized and externally differentiated for quite different purposes, but the superficial diversity serves only to emphasize, by contrast, the underlying identity of structure which persists intact beneath it. Thus, for example, the wing of a pigeon, the flipper of a whale, the foreleg of a cat, and the arm of a man are organs differing widely in function as well as outward appearance, but they are called homologous, none the less, because they all exhibit the same basic plan, being composed of similar bones similarly disposed with respect to one another.

Organs, on the other hand, are called analogous which, though fundamentally unlike in structure, are, nevertheless, superficially modified and specialized for one and the same function. The wing of a bird and the wing of an insect furnish a trite instance of such analogy. Functionally they subserve the same purpose, but structurally they bear no relation to each other. In like manner, though both are devoted to the same function, there exists between the leg of a man and the leg of a spider a fundamental disparity in structure.

At times, specialization for the selfsame function involves the emergence of a similar modification or uniform structural adaptation from a substrate of basic dissimilarity. In these instances of parallel modifications appearing on the surface of divergent types, we have something more than mere functional resemblance. Structure is likewise involved, albeit superficially, in the modification which brings about this external uniformity. In such cases, analogy is spoken of as convergence, a phenomenon of which the mole and the mole-cricket constitute a typical example. The burrowing legs of the insect are, so far as outward appearance goes, the exact replica on a smaller scale of those of the mole, though, fundamentally, their structure is quite unlike, the mole being built on the endoskeletal plan of the vertebrates, whereas the mole-cricket is constructed on the exoskeletal plan characteristic of the arthropods. Speaking of the first pair of legs of the mole-cricket, Thomas Hunt Morgan says: “By their use the mole-cricket makes a burrow near the surface of the ground, similar to, but of course much smaller than, that made by the mole. In both of these cases the adaptation is the more obvious, because, while the leg of the mole is formed on the same general plan as that of other vertebrates, and the leg of the mole-cricket has the same fundamental structure as that of other insects, yet in both cases the details of structure and the general proportions have been so altered that the leg is fitted for entirely different purposes from those to which the legs of other vertebrates and other insects are put.” (Quoted by Dwight in “Thoughts of a Catholic Anatomist,” p. 235.) In the analogies of convergence, therefore, we have the exact converse of the phenomenon so often encountered in connection with homology. The latter exhibits a contrast between basic identity and superficial diversity, the former a contrast between superficial convergence and fundamental divergence.

Now the extreme importance of homology is manifest from the fact that the taxonomists of zoölogy and botany have found it to be the most satisfactory basis for a scientific classification of animals and plants. In both of these sciences, organisms are arranged in groups according as they possess in common certain points of resemblance whereby they may be referred to this, or that, general type. The resemblance is most complete between members of the same species, which do not differ from one another by any major difference, though they may exhibit certain minor differences justifying their subdivision into varieties or races. These morphological considerations, however, must, in the case of an organic species, be supplemented by the additional physiological criteria of perfect sexual compatibility and normal viability, as we have already had occasion to note in the previous chapter. When organisms, though distinguished from one another by some major difference, agree, notwithstanding, in the main elements of structure, the several species to which they belong are grouped under a common genus, and similarly genera are grouped into families. A relative major difference, such as a difference in the size of the teeth, suffices for the segregation of a new species, while an absolute difference, such as a difference in the number of teeth or the possession of an additional organ, suffices for the segregation of a new genus. In practice, however, the classifications of systematists are often very arbitrary, and we find the latter divided into two factions, the “lumpers” who wish to reduce the number of systematic groups and the “splitters” who have a passion for breaking up larger groups into smaller ones on the basis of tenuous differences. Above the families are the orders, and they, in turn, are assembled in still larger groups called classes, until finally we reach the phyla or branches, which are the supreme categories into which the plant and animal kingdoms are divided. As we ascend the scale of classification, the points of resemblance between the organisms classified are constantly decreasing in number, while the points of difference increase apace. Hence, whereas members of the same species have very much in common, members of the same phylum have very little in common, and members of different phyla show such structural disparity that further correlation on the basis of similarities becomes impossible (in the sense, at least, of a reliable and consistent scheme of classification), all efforts to relate the primary phyla to one another in a satisfactory manner having proved abortive.

Within the confines of each phylum, however, homology is the basic principle of classification. But the scientist is not content to note the bare fact of its existence. He seeks an explanation, he wishes to know the raison d’être of homology. Innumerable threads of similarity run through the woof of divergence, and the question arises: How can we account for the coëxistence of this woof of diversity with a warp of similarity? Certainly, if called upon to explain the similarity existent between members of one and the same species, even the man in the street would resort instinctively to the principle of inheritance and the assumption of common ancestry, exclaiming: “Like sire, like son!” It is a notorious fact that children resemble their parents, and since members of the same species are sexually compatible and perfectly interfertile, there is no difficulty whatever in the way of accepting the presumption of descent from common ancestral stock as a satisfactory solution of the problem of specific resemblance. Now, it is precisely this selfsame principle of heredity which the Transformist invokes to account for generic, no less than for specific, similarity. In fact, he presses it further still, and professes to see therein the explanation of the resemblances observed between members of the different families, orders, and classes, which systematists group under a common phylum. This, of course, amounts to a bold extension of the principle of inheritance far beyond the barriers of interspecific sterility to remote applications that exceed all possibility of experimental verification. Transformists answer this difficulty, however, by contending that the period, during which the human race has existed, has been, geologically speaking, all too brief, and characterized by environmental conditions much too uniform, to afford us a favorable opportunity for ascertaining the extreme limits to which the genetic process may possibly extend; and, even apart from this consideration, they say, racial development (phylogeny) may be, like embryological development (ontogeny) an irreversible process, in which case no recurrence whatever of its past phenomena are to be expected in our times.

Be that as it may, the evolutionist interprets the resemblances of homology as surviving vestiges of an ancient ancestral type, which have managed to persist in the descendants notwithstanding the transformations wrought in the latter by the process of progressive divergence. Moreover, just as the existence of a common ancestor is inferred from the fact of resemblance, so the relative position in time of the common ancestor is inferred from the degree of resemblance. The common ancestor of forms closely allied is assumed to have been proximate, that of forms but distantly resembling each other is thought to have been remote. Thus the common ancestor of species grouped under the same genus is supposed to have been less remote than the common ancestor of all the genera grouped under one family. The same reasoning is applied, mutatis mutandis, to the ancestry of families, orders and classes.

The logic of such inferences may be questioned, but there is no blinking the fact that, in practice, the genetic explanation of homology is assumed by scientists to be the only reasonable one possible. In fact, so strong is their confidence in the necessity of admitting a solution of this kind, that they do not hesitate to make it part and parcel of the definition of homology itself. For instance, on page 130 of Woodruff’s “Foundations of Biology” (1922), we are informed that homology signifies “a fundamental similarity of structure based on descent from a common antecedent form.” The Yale professor, however, has been outdone in this respect by Professor Calkins of Columbia, who discards the anatomical definition altogether and substitutes, in lieu thereof, its evolutionary interpretation. “When organs have the same ancestry,” he says, “that is, when they come from some common part of an ancestral type, they are said to be homologous.” (“Biology,” p. 165.) In short, F. A. Bather is using a consecrated formula culled from the modern biological creed when he says: “The old form of diagnosis was per genus et differentiam. The new form is per proavum et modificationem.” (Science, Sept. 17, 1920, p. 259.)

A moment’s reflection, however, will make it clear that, in thus confounding the definition proper with its theoretical interpretation, the modern biologist is guilty of a logical atrocity. Homology, after all, is a simple anatomical fact, which can be quite adequately defined in terms of observation; nor is the definition improved in the least by having its factual elements diluted with explanatory theory. On the contrary, the definition is decidedly weakened by such redundancy. And as for those who insist on defining homology in terms of atavistic assumption instead of structural affinity, their procedure is tantamount to defining the clear by means of the obscure, an actual effect by means of a possible cause. Moreover, this attempt to load the dice in favor of Transformism by tampering with the definition of homology ends by defeating its own purpose. For, if homology is to serve as a legitimate argument for evolution, then obviously evolution must not be included in its definition; otherwise, the conclusion is anticipated in the premise, the question is begged, and the argument itself rendered a vicious circle.

Having formed a sufficiently clear conception of homology as a static fact, we are now in a position to consider the problem of its causality with reference to the solution proposed by evolutionists. Transmutation, they tell us, results from the interaction of a twofold process, namely, the conservative and similifying process called inheritance, and progressive and diversifying process known as variation. Inheritance by transmitting the ancestral likeness tends to bring about uniformity. Variation by diverting old currents into new channels adjust organisms to new situations and brings about modification. Homology, therefore, is the effect of inheritance, while adaptedness or modification is the product of variation.

As here used, the term inheritance denotes something more than a mere recurrence of parental characters in the offspring. It signifies a process of genuine transmission from generation to generation. Strictly speaking, it is not the characters, such as coloration, shape, size, chemical composition, structural type, and functional specificity, that are “inherited,” but rather the hereditary factors or chromosomal genes, which are actually transmitted, and of which the characters are but an external expression or manifestation. Hence, it is scarcely accurate to speak of “inherited,” as distinguished from “acquired,” characters. As a matter of fact, all somatic characters are joint products of the interaction of germinal and environmental factors. Consequently, the external character would be affected no less by a change in the environmental factors than by a change in the germinal factors. In a word, somatic characters are not the exclusive expression of the genetic factors, but are equally dependent upon environmental influence, and hence it is only to the extent that these characters are indicative of the specific constitution of the germ plasm that we may speak of them as “inherited,” remembering that what is really transmitted to the offspring is a complex of genes or germinal factors, and not the characters themselves. The sense is, therefore, that “inherited” characters are manifestative of what is contained in the germ plasm, whereas “acquired” characters have no specific germinal basis, but are a resultant of the interaction between the somatic cells and the environment. In modern terminology, as we have seen, the aggregate of germinal factors transmitted in the process of reproduction is called the genotype, while the aggregate of somatic characters which manifest these germinal factors externally is spoken of as the phenotype. Only the genotype is transmitted, the phenotype being the subsequent product of the interplay of genetic factors and environmental stimuli, dependent upon, and expressive of, both.

Variation, therefore, may be based upon a change in the germ plasm, or in the environment, or in both. If it rests exclusively upon an extraordinary change in the environmental conditions, the resulting modification is non-inheritable, and will disappear so soon as the exceptional environmental stimulus that evoked it is withdrawn. If, on the contrary, it is based upon a germinal change, it will manifest itself, even under ordinary, i.e. unchanged or uniform environmental influence. In this case, the modification is inheritable in the sense that it is the specific effect of a transmissible germinal factor, which has undergone alteration.

As we have seen in the foregoing chapter, there are three kinds of germinal change which result in “inheritable” modifications. The first is called factorial mutation, and is initiated by an alteration occurring in one or more of the chromosomal genes. The second is called chromosomal mutation, and is caused by duplication (or reduction) of the chromosomes. The third may be termed recombination, one type of which results from the crossover or exchange of genes between pairing chromosomes (“pseudomutation”), the other from random assortment in accordance with the Mendelian law of the independence of allelomorphic pairs. This so-called “random assortment of the chromosomes” is the result of the shuffling and free deals of the chromosomal cards of heredity which take place twice in the life-cycle of organisms: viz. first, in the process of gametic reduction (meiosis); second, in the chance meeting of variously-constituted sperms and eggs in fertilization. A mischance of the first of these “free deals” is bewailed in the following snatch from a parody belonging to the Woods Hole anthology.

“Oh chromosomes, my chromosomes,

How sad is my condition!

My grandsire’s gift for writing well

Has gone to some lost polar cell

And so I write this doggerel,

I cannot do much better.”

These kinds of variation, however, in so far as they fall within the range of actual observation, are confined within the limits of the organic species. Intra-specific variation, however, will not suffice. To account for the adaptive modifications superimposed upon underlying structural identity, Transformism is obliged to assume the possibility of trans-specific variation. Yet in none of the foregoing processes of variation do we find a valid factual basis for this assumption.

Factorial mutation, for instance, waiving its failure to produce naturally-viable forms, or to meet the physiological sterility test of a new species, admits of interpretation as a change of loss due to the “dropping out” of a gene from the germinal complex. Bateson’s conception of evolution as a process consisting in the gradual loss of inhibitive genes, whose elimination releases suppressed potentialities, seems rather incredible. Many will be inclined to see in Castle’s facetious epigram a reductio ad absurdum of Bateson’s suggestion; for, according to the latter’s view, as the Harvard professor remarks, we should have to regard man as a simplified amœba. Certainly, it seems nothing short of a contradiction to ascribe the progressive complication of the phenotype to a simplification of the genotype by loss.

On the other hand, not only is there no experimental evidence of a germinal change by positive acquisition, that is, by the addition of genes, but it is hard to conceive how such a change could come about. “At first,” admits Bateson, “it may seem rank absurdity to suppose that the primordial form or forms of protoplasm could have contained complexity enough to produce the divers types of life.” “But,” he asks, “is it easier to imagine that these powers could have been conveyed by extrinsic addition? Of what nature could these additions be? Additions of material can not surely be in question. We are told that salts of iron in the soil may turn a pink hydrangea blue. The iron cannot be passed on to the next generation. How can iron multiply itself? The power to assimilate iron is all that can be transmitted. A disease-producing organism like the pebrine of silkworms can in a very few cases be passed on through the germ cells. But it does not become part of the invaded host, and we can not conceive it taking part in the geometrically ordered processes of segregation. These illustrations may seem too gross; but what refinement will meet the requirements of the problem, that the thing introduced must be, as the living organism itself is, capable of multiplication and of subordinating itself in a definite system of segregation?” (Heredity, Smithson. Inst. Rpt. for 1915, p. 373.)

Nor can we agree with Prof. T. H. Morgan’s contention that the foregoing difficulty of Bateson has been solved by the discovery of the chromosomal mutation. All unbalanced chromosomal mutants are subnormal in their viability and vitality, not to speak of their marked sterility. Haploidy represents a regressive, rather than a progressive, step. The triploid mutant is sterile. The tetraploid race of Daturas is inferior in fertility to the normal diploid plant. The origin of balanced tetraploidy from diploidy must be presumed, since it has never been observed. Moreover, tetraploidy represents only quantitative, and not qualitative, progress. The increased mass of the nucleus produces an enlargement of the cytoplasm, the result of which is giantism. This effect, however, is not specific; for giant and normal races possessing each the same number of chromosomes are known to exist in nature. Hence giantism may be due to other causes besides chromosomal duplication. The only effect of this doubling is a reinforcement and intensification of the former effect of the genetic factors, their specificity remaining unchanged. Double doses are substituted for single doses of the factors, but nothing really new is added. Morgan himself recognizes that this mere repetition of identical genes is insufficient, and that their multiplication must be qualitative as well as numerical, to answer the specifications of a progressive step in evolution. Hence he suggests that the chromosomal mutation is subsequently supplemented by appropriate factorial mutation. Once this supposition is made, however, all the objections we have mentioned in connection with factorial mutation (e.g. the subnormality of its products, its intra-specific nature, etc.) return to plague the speculator, and, in addition to these, he is confronted with the new difficulty of explaining how the redundance of duplicate genes can be removed and replaced by coördinate differentiation in their respective specificities. Now we have no factual evidence whatever of such a solidaric redifferentiation of the germinal factors, that would modify harmoniously the composition and rôle of each and every gene in the factorial complex. Nor is there any possibility whatever of accounting for this telic superregulation of the germinal regulators upon a purely mechanistic basis. How can the ultimate chemical determinants of heredity be thus redetermined? Consequently, although there is gametic incompatibility between diploid races and the tetraploid races, which are said to have arisen from the former, we are not, nevertheless, warranted, by what has been experimentally verified, in regarding tetraploid races as new species, or as progressive steps in the process of organic evolution.

To conclude, therefore, we have experimental verification of the efficacy of the similifying process said to have been at work in evolution, namely, inheritance. The same, however, cannot be said of the correlative diversifying process of trans-specific variation, which is said to have superficially modified old structures into new species. The latter process, accordingly, is but a pure postulate of science known to us only through the effect hypothetically assigned to it, namely, the adaptive modification.

The adaptation, however, of which there is question here is not to be confounded with the “acquired adaptation” of Lamarckian fame; for, unlike the latter, it is an inheritable modification rooted in the germ plasm. Adaptations of this sort do, indeed, adjust the organism to its external environment, but they are innate and not acquired. Hence they are often spoken of as preadaptations; for they precede, in a sense, the organism’s contact with the environing element to which they adjust it. They may possibly, it is true, have been acquired in the distant past, but they have now a specific germinal foundation, and no one was ever privileged to witness their initial production de novo. The whale, for example, though fundamentally a warm-blooded mammal, is superficially a fish, by reason of such a preadaptation to its marine environment. Preadaptation is of common occurrence, especially among parasites, symbiotes, commensals, and inquilines. Wasmann cites innumerable instances of beetles and flies so profoundly modified, in accommodation to their mode of life as guests in termite nests, that the systematist hesitates to classify them under any of the accepted orders of insects. Here the adaptive modification so disturbs the underlying homology as to make of these creatures taxonomical ambiguities. In the case of Termitomyia, he tells us, “the whole development of the individual has been so modified that it resembles that of a viviparous mammal rather than that of a fly.” (“The Problem of Evolution,” pp. 14, 15.)

Such modifications, however, amount to major, and not merely minor, differences. We are not dealing, therefore, with varietal distinctions here, but with specific, generic, and even ordinal differences. With reference to the phenomenon of adaptive modification,[3] three things, consequently, are worthy of note: (1) it has the semblance of being adventitious to the underlying structural uniformity; (2) it is of such magnitude that it cannot be ascribed to variation within the species; (3) it has been appropriated by the hereditary process, in the sense that it is now an “inherited” character based on the transmission of specific germinal factors.

Now it is claimed that for the occurrence of this kind of modification in conjunction with homology only one rational explanation is possible, and that explanation is evolution. If this contention be a sound one, and Dorlodot, who claims certitude for the evolutionary solution, insists that it is such, then, in the name of sheer logical consistency, but one course lies open to us. We cannot stop at Wasmann’s comma,[4] we must press on to the very end of the evolutionary sentence and sing with the choristers of Woods Hole:

“It’s a long way from Amphioxus,

It’s a long way to us;

It’s a long way from Amphioxus,

To the meanest human cuss.

Good-bye fins and gill slits;

Welcome skin and hair.

It’s a long, long way from Amphioxus,

But we came from there.”

In this predicament it will not do, as we shall see presently, to adopt Mr. McCann’s expedient of balancing anatomical differences against anatomical resemblances. To do so is to court certain and ignominious defeat. We must, therefore, examine the argument dispassionately. If it be solid, we must accept it and give it general application. If it be unsound, we must detect its flaws and expose them. Intellectual honesty allows us no alternative!

Moreover, in weighing the argument from organic homology we must not lose sight of the two important considerations previously stressed: (1) that the inference of common ancestry in the case of homologous forms is based, not upon this or that particular likeness, but upon an entire group of coördinated resemblances; (2) that the resemblances involved are not exterior similarities, but deep-seated structural uniformities perfectly compatible with diversities of a superficial and functional character. “Nothing,” says Dr. W. W. Keen, “could be more unlike externally than the flipper of a whale and the arm of a man. Yet you find in the flipper the shoulderblade, humerus, radius, ulna, and a hand with the bones of four fingers masked in a mitten of skin.” (Science, June 9, 1922, p. 605.)

In fact, the resemblances may, in certain instances, be so deeply submerged that they no longer appear in the adult organism at all and are only in evidence during a transitory phase of the embryological process. In such cases, the embryo or larva exhibits, at a particular stage, traces of a uniformity completely obliterated from the adult form. In short, though frequently presented as a distinct argument, embryological similarity, together with all else of value that can still be salvaged from the wreck of the Müller-Haeckel Law of Embryonic Recapitulation, is, at bottom, identical with the general evolutionary argument from homology. In the latter argument we are directed to look beneath the modified surface of the adult organism for surviving vestiges of the ancestral type. In the former, we are bidden to go deeper still, to the extent, that is, of descending into the very embryological process itself, in order to discover lingering traces of the ancestral likeness, which, though now utterly deleted from the transformed adult, are yet partially persistent in certain embryonic phases.

In sectioning a larval specimen of the fly-like termite-guest known as Termitoxenia Heimi, Father Wasmann came across a typical exemplification of this embryological atavism. In the adult insect, a pair of oar-like appendages replace the wings characteristic of the Diptera (flies). These appendages are organs of exudation, which elaborate a secretion whereof the termites are very fond, and thereby render their possessors welcome guests in the nests of their hosts. The appendages, therefore, though now undoubtedly inherited characters, are the specific means by which these inquilines are adapted to their peculiar environment and mode of life among the termites. Moreover, the organs in question not only differ from wings functionally, but, in the adult, they bear no structural resemblance whatever to the wings of flies. Nevertheless, on examining his sections of the above-mentioned specimen, Wasmann found a developmental stage of brief duration during which wing veins appeared in the posterior branches of the embryonic appendages. Now, assuming that Wasmann’s technique was faultless, his specimen normal, and his interpretation correct, it is rather difficult to avoid his conclusion that we have here, in this transitory larval phase, the last surviving vestige of ancestral wings now wholly obliterated from the adult type, that, consequently, this wingless termite guest is genetically related to the winged Diptera, and that we must see in the appendages aboriginal wings diverted from their primitive function and respecialized for the quite different purpose of serving as organs of exudation, (cf. “Modern Biology,” p. 385.) Indeed, phenomena of this kind seem to admit of no other explanation than the atavistic one. It should be remembered, however, that Wasmann does not appear to have verified the observation in more than one specimen, and that a larger number of representative specimens would have to be accurately sectioned, strained, examined and interpreted, before any reliable conclusion could be drawn.[5]

Such, in its most general aspect, is the atavistic solution of the problem presented by the homology of types. In it, similarity and diversity are harmoniously reconciled, in the sense that they affect, respectively, different structural, or different developmental, levels. It is futile, therefore, to look for contradictions where they do not exist. In a word, the attempt to create opposition between a group of basic and correlated uniformities, on the one hand, and some particular external difference, on the other, is not only abortive, but absolutely irrelevant as well. The reason is obvious. Only when likeness is associated with unlikeness is it an argument for Transmutation. Likeness alone would demonstrate Immutability by indicating a process of pure inheritance as distinguished from the process of variation. Hence evolutionists do not merely concede the coëxistence of diversity with similarity, they gladly welcome this fact as vitally necessary to their contention.

Now it is precisely this point which Mr. McCann, like many other critics of evolution, fails utterly to apprehend. Consequently, his efforts to extricate the human foot from the toils of simian homology are entirely unavailing. To offset the force of the argument in question, it is by no means sufficient, as he apparently imagines, to point to the fact that, unlike the hallux of the ape, the great toe in man is non-opposable (cf. “God—or Gorilla,” pp. 183, 184, and legends under cuts opposite pp. 184 and 318). The evolutionist will reply at once that the non-opposability of man’s great toe is correlated with the specialization of the human foot for progression only, as distinguished from prehension; while, in the ape, whose foot has retained both the progressive and the prehensile function, the hallux is naturally opposable in adaptation to the animal’s arboreal habits. He will then call attention to the undeniable fact that, despite these adaptational differences, the bones in the foot of a Troglodyte ape are, bone for bone, the counterparts of the bones in the human foot and not of those in the human hand. He will readily concede, that, so far as function and adaptedness go, this simian foot is a “hand,” but he will not fail to point out that it is, at the same time, a heeled hand equipped with a calcaneum, a talus, a navicular, a cuboid, and all other structural elements requisite to ally it to the human foot and distinguish it from the human hand. In fact, Mr. McCann’s own photographs of the gorilla skeleton show these features quite distinctly, though he himself, for some reason or other, fails to speak of them. It is to be feared, however, that his adversaries may not take a charitable view of his reticence concerning the simian heel, but may be inclined to characterize his silence as “discreet,” all the more so, that he himself has uncomplimentarily credited them with similar discretions in their treatment of unmanageable facts. In short, Mr. McCann’s case against homology resembles the Homeric hero, Achilles, in being vulnerable at the “heel.” At all events, the homology itself is an undeniable fact, and it is vain to tilt against this fact in the name of adaptational adjustments like “opposability” and “non-opposability.” Since, therefore, our author has failed to prove that this feature is too radical to be classed as an adaptive modification, our only hope of exempting the human skeleton from the application of the argument in question is to show that argument itself is inconsequential.

Mr. McCann’s predicament resembles that of the unlucky disputant, who having allowed a questionable major to pass unchallenged, strives to retrieve his mistake by picking flaws in a flawless minor. As Dwight has well said of the human body, “it differs in degree only from that of apes and monkeys,” and “if we compare the individual bones with those of apes we cannot fail to see the correspondence.” (“Thoughts of a Catholic Anatomist,” p. 149.) In short, there exists no valid anatomical consideration whatever to justify us in subtracting the human frame from the extension of the general conclusion deduced from homology. Whosoever, therefore, sees in the homology of organic forms conclusive evidence of descent from a common ancestor, cannot, without grave inconsistency, reject the doctrine of the bestial origin of man. He may still, it is true, exclude the human mind or soul from the evolutionary account of origins, but, if homology is, in any sense, a sound argument for common descent, the evolutionary origin of the human body is a foregone conclusion, and none of the anatomical “differences in degree” will avail to spare us the humiliation of sharing with the ape a common family-tree. It remains for us, then, to reëxamine the argument critically for the purpose of determining as precisely as possible its adequacy as a genuine demonstration.

To begin with, it must be frankly acknowledged that here the theory of transformism is, to all appearances, upon very strong ground. Its first strategic advantage over the theory of immutability consists in the fact that, unlike the latter, its attitude towards the problem is positive and not negative. When challenged to explain the structural uniformities observed in organic Nature, the theory of immutability is mute, because it knows of no second causes or natural agencies adequate to account for the facts. It can only account for homology by ascribing the phenomenon exclusively to the unity of the First Cause, and, while this may, of course, be the true and sole explanation, to assume it is tantamount to removing the problem altogether from the province of natural science. Hence it is not to be wondered at that scientists prefer the theory of transformism, which by assigning intermediate causes between the First Cause and the ultimate effects, vindicates the problem of organic origins for natural science, in assuming the phenomena to be proximately explicable by means of natural agencies. Asked whether he believes that God created the now exclusively arboreal Sloth (Bradypus) in a tree, the most uncompromising defender of fixism will hesitate to reply in the affirmative. Yet, in this case, what is nowadays, at least, an inherited preadaptation, dedicates the animal irrevocably to tree-life, and makes its survival upon the ground impossible.

Analogous preadaptations occur in conjunction with the phenomena of parasitism, symbiosis and commensalism, all of which offer instances of otherwise disparate and unrelated organisms that are inseparably bound together, in some apparently capricious and fortuitous respect, by a preadaptation of the one to the other. Parasites, guests, or symbiotes, as the case may be, they are now indissolubly wedded to some determinate species of host by reason of an appropriate and congenital adjustment. For all that, however, the association seems to be a contingent one, and it appears incredible that the associates were always united, as at present, by bonds of reciprocal advantage, mutual dependence, or one-sided exploitation. Yet the basis of the relationship is in each case a now inherited adaptation, which, if it does not represent the primitive condition of the race, must at some time have been acquired. For phenomena such as these, orthogenesis, which makes an organ the exclusive product of internal factors, conceiving it as a preformed mechanism that subsequently selects a suitable function, has no satisfactory explanation. Lamarckism, which asserts the priority of function and makes the environment mold the organ, is equally inacceptable, in that it flouts experience and ignores the now demonstrated existence of internal hereditary factors. But, if between these two extremes some evolutionary via media could be found, one must confess that it would offer the only conceivable “natural explanation” of preadaptation.[6] All this, of course, is pure speculation, but it serves to show that here, at any rate, the theory of Transformism occupies a position from which it cannot easily be dislodged.

But, besides the advantage of being able to offer a “natural explanation” of the association of homology with adaptation, Transformism enjoys the additional advantage of being able to make the imagination its partisan by means of a visual appeal. Such an appeal is always more potent than that of pure logic stripped of sensuous imagery. When it comes to vividness and persuasiveness, the syllogism is no match for the object-lesson. Retinal impressions have a hypnotic influence that is not readily exorcised by considerations of an abstract order—“Segnius irritant demissa per aurem, Quam quae sunt oculis subjecta fidelibus,” says Horace, in the “Ars Poetica.” Philosophers may distinguish between the magnetic appeal of a graphic presentation and the logical cogency of the doctrine so presented, but there is no denying that, in practice, imagination is often mistaken for reason and persuasion for conviction. Be that as it may, the ordinary method of bringing home to the student the evolutionary significance of homology is certainly one that utilizes to the full all the advantages of visual presentation. Given a class of impressionable premedics and coeds; given an instructor’s table with skeletons of a man, a flamingo, an ape and a dog hierarchically arranged thereon; given an instructor sufficiently versed in comparative osteology to direct attention to the points in which the skeletons concur: and there can be no doubt whatever as to the psychological result. The student forms spontaneously the notion of a common vertebrate type, and the instructor assures him that this “general type” is not, as it would be with respect to other subject matter, a mere universal idea with no formal existence outside the mind, but rather a venerable family likeness, posed for originally by a single pair of ancestors (or could it possibly have been, by one self-fertilizing hermaphrodite?) and recopied from generation to generation, with certain variations on the original theme, by the hand of an artist called Heredity. This explanation may be true, but logically consequential it is not. However, if the dialectic is poor, the pedagogy is beyond reproach, and the solution proposed has in its favor the fact that it accords well with the student’s limited experience. He is aware of the truism that children resemble their parents. Why look for more recondite explanations when one so obvious is at hand? The atavistic theory gratifies his instinct for simplification, and, if he be of a mechanistic turn of mind, the alternative conception of creationism is quite intolerable. Nevertheless, it goes without saying that the “inference” of common descent from the data of homology is not a ratiocination at all, it is only a simple apprehension, a mere abstraction of similarity from similars—“Unde quaecumque inveniuntur convenire in aliqua intentione intellecta,” says Aquinas, “voluerunt quod convenirent in una re.” (In lib. II sent., dist. 17, q. I, a. 1) Philosophy tells us that the oneness of the universal is conceptual and not at all extramental or real, but the transformist insists that the universal types of Zoölogy and Botany are endowed with real as well as logical unity, that real unity being the unity of the common ancestor.

Certainly, from the standpoint of practical effectiveness, the evolutionary argument leaves little to be desired. The presentation is graphic and the solution simple. But for the critic, to whom logical sequence is of more moment than psychological appeal, this is not enough. To withstand the gnawing tooth of Time and the remorseless probing of corrosive human reason, theories must rest on something sounder than a mirage of visual imagery!

Tell me where is fancy bred,

Or in the heart or in the head?

How begot, how nourished?

Reply, reply.

It is engendered in the eyes,

With gazing fed; and fancy dies

In the cradle where it lies.

But is it fair thus to characterize the “common ancestors” of Transformism as figments which, like all other abstractions, have no extramental existence apart from the concrete objects whence they were conceived? To be sure, their claim to be real entities cannot be substantiated by direct observation or experiment, and so a factual proof is out of the question. Man, the late-comer, not having been present at the birth of organic forms, can give no reliable testimony regarding their parentage. In like manner, no a priori proof from the process of inheritance is available, because heredity, as revealed to us by the experimental science of Genetics, can account for specific resemblances only, and cannot be invoked, at present, as an empirically tested explanation for generic, ordinal, or phyletic resemblances. It has still to be demonstrated experimentally that the hereditary process is transcendental to limits imposed by specific differentiation. There remains, however, the a posteriori argument, which interprets homology and adaptation as univocal effects ascribable to no other agency than the dual process of inheritance and variation. What are we to think of this argument? Does it generate certainty in the mind, or merely probability?

A moment’s reflection will bring to light the preliminary flaw of incomplete enumeration of possibilities. To suppose that inheritance alone can account for structural resemblance is an unwarranted assumption. Without a doubt, there are other similifying influences at work in Nature besides inheritance. True, inheritance is one possible explanation of the similarity of organisms, but it is not the only one. Even among the chemical elements of inorganic nature we find analogous uniformities or “family traits,” which, in the absence of any reproductive process whatever, we cannot possibly attribute to inheritance. Mendeléeff’s discovery of the periodicity of the elements, arranged in the order of their atomic weights, is well-known. At each interval of an octave, a succession of chemical types, similar to those of the preceding octave, recur. Hence elements appearing in the same vertical column of the Periodic Table have many properties in common and exhibit what may be called a family resemblance. Now, we have in the process of atomic disintegration, as observed in radioactive elements and interpreted by the electronic theory of atomic structure, a reasonably satisfactory basis upon which to account for the existence of these inorganic uniformities. Here analogous chemical constitution, produced in accordance with a general law, results in uniformity that implies a similar, rather than an identical, cause. The hypothesis of parallelistic derivation from similar independent origins accounts quite as well for the observed uniformities as does the hypothesis of divergent derivation from a single common origin. Why, then, should we lean so heavily on the already overtaxed principle of inheritance, when parallelism is as much a possibility in the organic world as it is an actuality in the inorganic world?

As to the contrast here drawn between inheritance and other similifying factors, it is hardly necessary to remark that we are speaking of inheritance as defined in terms of Mendelian experiment and cytological observation. In the so-called chemical theory of inheritance, the distinction would be meaningless and the contrast would not exist. Ehrlich’s disciple, Adami, sets aside all self-propagating germinal determinants, like the chromomeres, in favor of a hypothetical “biophoric molecule,” which is to be conceived as a benzine-like ring bristling with sidechains. Around this determining core the future organism is built up in definite specificity, as an arch is constructed about a template. Adami has merely applied Paul Ehrlich’s ideas concerning metabolism and immunity to the question of heredity, commandeering for this purpose the latter’s entire toolkit of receptors, haptophores, amboceptors, etc., as though this grotesque paraphernalia of crude and clumsy mechanical symbols (which look for all the world like the wrenches of a machinist, or the lifters used by the cook to remove hot lids from the kitchen range) could throw any valuable light whatsoever on the exceedingly complex, and manifestly vital, phenomenon of inheritance. It does not even deserve to be called a chemical theory, for, as Starling correctly remarks concerning Ehrlich’s conception, “though chemical in form,” it is not so in reality, because “it does not explain the phenomenon by reference to the known laws of chemistry.” (Cf. Physiology, ed. of 1920, p. 1084.) In a word, the theory of heredity, which seeks to strip inheritance of its uniqueness as a vital process by identifying it with the more general physicochemical processes occurring in the organism, is a groundless speculation, that, far from explaining, flouts the very observational data which it pretends to elucidate. Kurz und gut! to requite the mechanist, Schäfer, with his own Danielesque phrase, here, as elsewhere, the mechanists have succeeded in extracting from the facts, not what the facts themselves proclaim, but what preëxisted in their own highly-cultured imaginations so well-stocked with cogs, cranks, ball bearings, and other æsthetic imagery emanating from polytechnic schools and factories.

But in arguing from the existence of parallelism in the inorganic world to its possibility in the organic world, we are less liable to displease the mechanists than those other extremists, the neo-vitalists, who will be prone to deny all parity between living, and inanimate, matter. Fortunately, we are in a position to appease the scruples of the latter by referring to the facts of convergence as universally accepted evidence that the phenomenon of parallelism occurs in animate, no less than inanimate, nature. Admitting, therefore, that the laws of organic morphology are of a higher order than those which regulate atomic, molecular, and multimolecular structure, these facts attest, nevertheless, that parallelisms arise in organisms of separate ancestry which are due, not to heredity, but to the uniform action of universal morphogenetic forces. Hence general laws can be invoked to account for organic uniformities with the same right that they are invoked to account for resemblances existing between the various members of a chemical “family” like the Halogens. And why should this not be so? Organisms have much in common that transcends any possible scheme of evolution and that cannot be brought into alignment with the position arbitrarily assigned them in the evolutionary family-tree. They all originate as single cells. Their common means of growth and reproduction is mitotic cell division. This leads to the production of a somatella, among the protista, and of a soma differentiated by histogenesis into two or three primary tissues, among the metista. All these fundamental processes are strikingly uniform throughout the entire plant and animal world. In these universal properties of living matter, therefore, we have a common basis for general structural and organizational laws, which, though irreducible to the “common ancestors” of Transformism, is quite adequate to account for both the homologies and analogies of living matter. Accept this basis of general laws regulating the development of living matter, and there is no difficulty in seeing why the problems posed by exposure to analogous environmental conditions are solved in parallel fashion by organisms, irrespective of whether they are nearly, or distantly, related in the sense of morphology. Transformism, on the other hand, can only account for homology at the expense of convergence, and for convergence at the expense of homology. So far as a common ancestral basis is concerned, the two kinds of resemblance are, from the very nature of the case, irreducible phenomena.

It is only, in fact, by surrendering the principle that similarity entails community of origin, and by falling back on the suggested common basis of general laws, that Transformism makes room in its system for the troublesome facts of convergence. “It might be reiterated in passing,” says Dwight, “that this ‘convergence’ business is a very ticklish one. We have been taught almost word for word that resemblance implies relationship, or almost predicates it; but according to this doctrine it has nothing to do with it whatever.” (“Thoughts of a Cath. Anat.,” p. 190.) And in a subsequent chapter he says: “No very deep knowledge of comparative anatomy is needed for us to know that very similar adaptations for particular purposes are found in very diverse animals. The curious low grade mammal, the Ornithorhynchus, with a hairy coat and the bill of a duck, is a familiar instance. We all know that the whales have the general form of the fish, although they are mammals, and going more into details we know that the whale’s flipper is on the same general plan as that of the ancient saurians.... The origin of the eye, according to evolutionary doctrines, has been a very difficult problem, which gets worse rather than better the more you do for it. Even if we could persuade ourselves that certain cells blundered along by the lucky mating of individuals in whom they were a bit better developed than in the others till they came to form a most complicated organ of sight, it would be a sufficient tax on our credulity to believe that this could come off successfully in some extraordinary lucky species; but that it should have turned out so well with all kinds of vertebrates is really too much to ask us to swallow. But this is not all: eyes are very widely spread among different classes of invertebrates. More wonderful still, the eyes of certain molluscs and crustacea are on stalks, and this is found also in various and very different families of fishes. How did this happen? Was it by way of descent from the molluscs or the crustacea? If not, how could chance have brought about such a similar result in diverse forms?” (Op. cit., pp. 233-236.)

It may be objected that the resemblances of convergence are superficial analogies, not to be confounded with fundamental homologies. This contention may be disputed; for, as we shall see in the next chapter, there are cases where the convergence is admittedly radical, and not merely superficial. The distinction, moreover, between shallow and basic characters is somewhat arbitrary, and its validity is often questionable. When the skeletal homology that relates the amphibia to the mammals, for instance, is traced to the root of the vertebrate family tree, we find it all but disappearing in a primitive Amphioxus-like chordate, whose so-called skeleton contains no trace of bone or cartilage. Hence, if we go back far enough, the homologies of today become the convergences of a geological yesterday, and we find the vertebrate type of skeleton arising independently in reptiles, mammals, amphibia, and fishes.

Again, there are times when convergent analogies appear to be more representative of the common racial heritage than the underlying structure itself, tempting the evolutionist to fly in the face of the orthodox interpretation, which rigidly rules out analogy in favor of homology, and refuses to accept the eloquent testimony of a remarkable resemblance merely because of a slight technical discrepancy in the structural substrate. A large pinching claw, or chela, for example, occurs in two organisms belonging to the phylum of the arthropods, namely, the lobster and the African scorpion. Both chelæ are practically identical in structure, but, unfortunately, the chela of the lobster arises from a different appendage than that from which the scorpion’s chela emerges. If they arose from corresponding appendages, they would be pronounced “homologous organs” and acclaimed, without hesitation, as strong evidence in favor of the common origin of all the arthropods. In proof of this, we call attention to the importance attached to the adaptations affecting homologous bones in fossil “horses.” As it is, however, the two chelæ are analogous, and not homologous, organs. Hence, technically speaking, the two chelæ are utterly unrelated structures. To the eye of common sense, however, the likeness appears to be far more important than the difference, and the average person will be inclined to view the resemblance as evidence of a community of type. In fact, the tendency to discard superficial, and to retain only fundamental, uniformities, is dangerous to the theory of Transformism. When we confine our attention to what is really basic, we find that the resemblances become so generalized and widespread that specific conclusions as to descent become impossible, and we lose all sense of direction in a clueless labyrinth of innumerable, yet mutually contradictory, possibilities.

Finally, it may be noted in passing that, though it is customary with evolutionists to regard homologous characters as the tenaciously persistent heritage of primeval days, and to look upon adaptational characters as adventitious and accessory to the aforesaid primitive heritage, the supposedly older and more fundamental characters fail to give, by the manifestation of greater fixity, any empirical evidence whatever of their being more deeply or firmly rooted in the hereditary process than the presumably newer adaptational characters. We have, therefore, no experimental warrant for appropriating homologous, rather than adaptational, characters to the process of inheritance. “It is sometimes asserted,” says Goodrich, “that old-established characters are inherited, and that newly begotten ones are not, or are less constant, in their reappearance. This statement will not bear critical examination. For, on the one hand, it has been conclusively shown by experimental breeding that the newest characters may be inherited as constantly as the most ancient.... While, on the other hand, few characters in plants can be older than the green color due to chlorophyll, yet it is sufficient to cut off the light from a germinating seed for the greenness to fail to appear. Again, ever since Devonian times vertebrates have inherited paired eyes; yet, as Professor Stockard has shown, if a little magnesium chloride is added to the sea water in which the eggs of the fish Fundulus are developing, they will give rise to embryos with one median cyclopean eye! Nor is the suggestion any happier that the, so to speak, more deep-seated and fundamental characters are more constantly inherited than the trivial or superficial. A glance at the organisms around us, or the slightest experimental trial, soon convinces us that the apparently least important character may reappear as constantly as the most fundamental. But while an organism may live without some trivial character, it can rarely do so when a fundamental character is absent, hence such incomplete individuals are seldom met in Nature.” (Science, Dec. 2, 1921, p. 530.)

But, whether it be upon, or beneath, the surface, similitude of any kind suffices to establish our contention that inheritance is not the only similifying influence present in organisms, and that resemblance is perfectly compatible with independence of ancestry. We have, therefore, an alternative for inheritance in the explanation of organic uniformities, and by the admission of this alternative, which, for the rest, is factually attested by the universally acknowledged phenomena of convergence, the inference of common descent from structural resemblance is shorn of the last remnant of its demonstrative force, as an a posteriori argument.

But a still more serious objection to the evolutionary interpretation of homology and preadaptation arises from its intrinsic incoherency. Evolution, as previously stated, is assumed to be the resultant of a twofold process, namely, inheritance and variation. The first is a conservative and similifying process, which transmits. The second is a progressive and diversifying process, which diverts. To the former process are due the uniformities of homology, to the latter the deviations of adaptation. Upon the admission of evolutionists themselves, however, neither of these processes behaves in a manner consistent with its general nature, and both of them are flagrantly unfaithful to the principal rôles assigned to them. Nowadays the hereditary process transmits adaptational, as well as homologous, characters. If, then, adaptational characters are more recent than homologous characters, there must have been a time when inheritance ceased to similify and become a diversifying process by transmitting what it did not receive from the previous generation. There were times when, not content with simply reiterating the past, it began to divert former tendencies into novel channels. In other words, inheritance becomes dualized into a paradoxical process, which both perpetuates the old and appropriates the new. The same inconsistency is manifest in the process of variation, which capriciously produces convergent, no less than divergent, adaptations. In two fundamentally identical structures, like the wing of a bird and the foreleg of a cat, variation is said to have produced diverse adaptations. In two fundamentally diverse structures, like the head of an octopus and the head of a frog, variation is said to have produced an identical adaptation, namely, the vertebrate type of eye. It appears, therefore, that the essentially diversifying process of variation can become, on occasion, a simplifying process, which, instead of solving environmental problems in an original manner, prefers to employ uniform and standardized solutions, and to cling to its old stereotyped methods. Inheritance similifies and diversifies, variation converges and diverges. It is futile to attempt to reduce either of these protean processes to a condition that even approximates consistency. The evolutionist blows hot and cold with the same breath. Verily, his god is Proteus, or the double-headed Janus!

Summa summarum: The evolutionary argument from homology is defective in three important respects: (1) in its lack of experimental confirmation; (2) in its incomplete enumeration of the disjunctive possibilities; (3) in its inability to construct a scheme of transmutation that synthesizes inheritance and variation in a logically coherent, and factually substantiated formula. The first two defects are not necessarily fatal to the argument as such. Though they destroy its pretensions to conclusiveness, they do not preclude the fulfilment of the moderate claim made in its behalf by Prof. T. H. Morgan, who says: “In this sense (i.e., as previously stated) the argument from comparative anatomy, while not a demonstration, carries with it, I think, a high degree of probability.” (“A Critique of the Theory of Evolution,” p. 14.) The third defect is more serious. The apparently irreducible antagonism which the evolutionary assumption introduces between inheritance and variation has been sensed even by the adherents of transformism themselves, and they have searched in vain for a formula, which, without sacrificing the facts, would bring into concord the respective rôles of these discordant factors. “It follows,” says Osborn, “as an unprejudiced conclusion from our present evidence that upon Weismann’s principle we can explain inheritance but not evolution, while with Lamarck’s principle and Darwin’s selection principle we can explain evolution, but not, at present, inheritance. Disprove Lamarck’s principle and we must assume that there is some third factor in evolution of which we are ignorant.” (Popular Science Monthly, Jan., 1905.) The point is well taken, and unless, as Osborn suggests, there is a tertium quid by means of which the discord can be resolved into ultimate harmony, we see no way of liberating the theory of Transmutation from this embarrassing dilemma.

CHAPTER III
FOSSIL PEDIGREES

“By dint of such great efforts we succeeded only in piecing together genial romances more or less historical.”—B. Grassi, Prof. of Comparative Anatomy, Univ. of Rome, “La vita” (1906), p. 227.

§ 1. The Argument in the Abstract

The palæontological argument for evolution is based upon the observed gradual approximation in type of the earlier forms of life, as represented by the fossils still preserved in successive geological strata, to the later forms of life, as represented by the contemporary species constituting our present flora and fauna. Here the observed distribution in time supplements and confirms the argument drawn from mere structural affinity. Here we are no longer dealing with the spatial gradation of contemporary forms, arranged on a basis of greater or lesser similarity (the gradation whence the zoölogist derives his argument for evolution), but with a temporal gradation, which is simultaneously a morphological series and an historical record. The lower sedimentary rocks contain specimens of organic life very unlike modern species, but, the higher we ascend in the geological strata, the more closely do the fossil forms resemble our present organisms. In fact, the closeness of resemblance is directly proportional to the proximity in time, and this seems to create a presumption that the later forms of life are the modified descendants of the earlier forms. Considered in the abstract, at least, such an argument is obviously more formidable than the purely anatomical argument based on the degrees of structural affinity observable in contemporary forms. It ought, therefore, to be extremely persuasive, provided, of course, it proceeds in rigorous accord with indubitably established facts and rules out relentlessly the alloy of uncritical assumptions.

Here, likewise, we find the theory of transformism asserting its superiority over the theory of immutability, on the ground that evolutionism can furnish a natural explanation for the gradational distribution of fossil types in the geological strata, whereas the theory of permanence resorts, it is said, to a supernaturalism of reiterated “new creations” alternating with “catastrophic exterminations.” Now, if this claim is valid, and it can be shown conclusively that fixism is inevitably committed to a postulate of superfluously numerous “creations,” then the latter theory is shorn of all right to consideration by Occam’s Razor: Entia non sunt multiplicanda sine ratione. It is rather difficult to conceive of the Creator as continually blotting out, and rewriting, the history of creation, as ruthlessly exterminating the organisms of one age, only to repopulate the earth subsequently with species differing but little from their extinct predecessors—ad quid perditio haec? Such procedure hardly comports with the continuity, regularity and irrevisable perfection to be expected in the works of that Divine Wisdom, which “reacheth ... from end to end mightily and disposeth all things sweetly” (Wisdom, viii; 1), which “ordereth all things in measure, and number and weight.” (Wis. xi; 21.)

Following the lead of other evolutionists, Wasmann has striven to saddle fixism with the fatuity of periodic catastrophism and “creation on the installment plan.” But even Cuvier, who is credited with having originated the theory of catastrophism, did not go to the absurd extreme of hypothecating reiterated creations, but sought to explain the repopulation of the earth after each catastrophe by means of migrations from distant regions unaffected by the catastrophe. Historically, too, fixism has had its uniformitarian, as well as its catastrophic, versions. In fact, Huxley classifies both uniformitarianism and catastrophism as fixistic systems, when he says: “I find three more or less contradictory systems of geologic thought ... standing side by side in Britain. I shall call one of them Catastrophism, another Uniformitarianism, the third Evolutionism.” (“Lay Sermons,” p. 229.) Obviously, then, fixism is separable from the hypothesis of repeated catastrophes alternating with repeated “creations.” Stated in proper terms, it is at one with evolutionism in rejecting as undemonstrated and improbable the postulate of reiterated cataclysms. It freely acknowledges that, in the absence of positive evidence of their occurrence, the presumption is against extraordinary events, like wholesale catastrophes. It sanctions the uniformitarian tenet that ordinary cosmic processes are to be preferred to exceptional ones as a basis of geological explanation, and it repudiates as unscientific any recourse to the unusual or the miraculous in accounting for natural phenomena. Its sole point of disagreement with evolutionism is its refusal to admit organic changes of specific magnitude. It does, however, admit germinal changes of varietal magnitude. It also recognizes that the external characters of the phenotype are the joint product of germinal factors and environmental stimuli, and admits, in consequence, the possibility of purely somatic changes of considerable profundity being induced by widespread and persistent alterations in environmental conditions. Like Darwin, the uniformitarian fixist ascribes the origination of organic life to a single vivifying act on the part of the Creator, an act, however, that was formative rather than creative, because the primal forms of life, whether few or many, were all evolved through Divine influence from preëxistent inorganic matter. Unlike Darwin, he ascribes the continuation of organic life to generative processes that were univocal (generationes univocae), and not gradually-equivocal (generationes paulatim aequivocae). In the next chapter, we shall see that, in attributing the initial formation of species to a Divine act, neither Darwin nor the creationists exposed themselves to the charge of explaining the “natural” by means of the “miraculous.” And, as for the process by which living forms were continued upon earth, the univocal reproductive process upheld by fixism is more manifestly a natural process than the gradually-equivocal generation of variable inheritance hypothecated by the theory of transmutation. The sole matter of dispute between the two views is whether the life-cycles of organisms are circles or spirals.

But all this, it will be said, is purely negative. Merely to refrain from any recourse to the extraordinary or the supernatural is by no means sufficient. “Natural explanations” must be explanatory as well as natural. Unless there be a simplification, a reduction of plurality to unity, a resolution of many particular problems into a common general problem, we have no explanation worthy of the name. Granting, therefore, that uniformitarian fixism does not recur to the anomalous or the miraculous, it still lies open to the charge of failing in its function as an explanation, because it multiplies origins in both space and time. Transformism, on the contrary, is said to elucidate matters, inasmuch as it unifies origins spatially and temporally.

That transformism successfully plausibleizes a unification of origins in space, is true only in a limited and relative sense. The most that can be said for the assumption, that resemblances rest on the principle of common inheritance, is that it permits of a numerical reduction of origins, but this numerical reduction will, by an intrinsic necessity, always fall short of absolute unification. The monophyletic derivation of all organic forms from one primordial cell or protoblast is a fantastic dream, for which, from the very nature of things, natural science does not, and can not, furnish even the semblance of an objective basis. The ground is cut from under our feet, the moment we attempt to extend the principle of descent outside the limits of an organic phylum. The sole basis of inference is a group of uniformities, and, unless these uniformities predominate over the diversities, there can be no rational application of the principle of transformism. Hence, the hypothesis, that organisms are consanguineous notwithstanding their differences, loses all value as a solution at the point where resemblances are outweighed by diversities. The transmutation assumed to have taken place must be never so complete as to have obliterated all recognizable vestiges of the common ancestral type. “Whenever,” says Driesch, “the theory that, in spite of their diversities, the organisms are related by blood, is to be really useful for explanation, it must necessarily be assumed in every case that the steps of change, which have led the specific form A to become the specific form B, have been such as only to change in part that original form A. That is to say: the similarities between A and B must never be overshadowed by their diversities.” (“Science and Philosophy of the Organism,” v. I, p. 254.) When, therefore, the reverse is true and diversities are prevalent over uniformities, we are left without clue or compass in the midst of a labyrinth of innumerable possibilities. Such are the limits imposed by the very nature of the evidence itself, and the scientists, who transgress these limits, by attempting to correlate the primary phyla, are on a par with those unconvincible geniuses, who continually besiege the Patent Office with schemes ever new and weird for realizing the chimera of “perpetual motion.”

Thus scientific transformism is unable to simplify the problem beyond a certain irreducible plurality of forms, lesser only in degree than the plurality postulated by fixism. This being the case, the attempts of Wasmann and Dorlodot to prune the works of Creation with Occam’s Razor are not only presumptuous, but precarious as well. Qui nimis probat, nihil probat! If it be unworthy of God to multiply organic origins in space, then monophyletic descent is the only possible alternative, and polyphyletic transformism falls under the same condemnation as fixism. Yet the polyphyletic theory of descent is that to which both Wasmann and Dorlodot subscribe, as it is, likewise, the only kind of transformism which science can ever hope to plausibleize. Besides, too close a shave with Occam’s Razor would eliminate creation altogether, since all theologians cheerfully admit that it was the result of a free and unnecessary act on the part of God. When we apply our rationes convenientiae to the Divine operations, we must not make the mistake of applying them to the Divine action itself instead of the created effects of that action. We may be competent to discern disorder and irregularity in finite things, but we are wholly incompetent to prescribe rules for Divine conduct. To say that God is constrained by His infinite Wisdom to indirect, rather than direct, production, or that He must evolve a variety of forms out of living, rather than non-living, matter, is to be guilty of ridiculous anthropomorphism. There is no a priori reason, founded upon the Divine attributes, which restricts God’s creative action to the production of this, or that, number of primordial organisms, or which obliges him to endow primitive organisms with the power of transmutation.

But the fact that these rationes convenientiae fail to establish the a priori necessity of a unification of organic origins in space, does not imply that they are without value in suggesting the unification of organic origins in time. Order and regularity are not excluded by spatial multiplicity, but they may easily be excluded by the incongruities of an irregular succession of events. Indeterminism and chance are, indeed, inseparable from the course of Nature. There is in matter an unlimited potentiality, incommensurate with the limited efficacy of natural agencies. Hence it evades the absolute control of all finite factors and forces. But the anomalies and irregularities, which are contingent upon the limitation or frustration of second causes unable to impose an iron necessity upon evasive matter, are not referable to the First Cause, but rather to the finite efficacy of second causes. Such anomalies in natural processes, consequently, are not inconsistent with infinite wisdom and power on the part of the Creator. If, on the contrary, the anomaly occurs, not in the form of an accidental frustration of a natural agency, but in the form of an intrusive “new creation,” the irregularity in question would then be referable to the Creator Himself, and such derogations of order are inadmissible, except as manifestations of the supernatural. In fact, the abrupt and capricious insertion of a “new creation” into an order already constituted, say, for instance, the sudden introduction of Angiosperms in the Comanchian period, or of mammals in the Tertiary, would be out of harmony with both reason and revelation. Unless there is a positive reason for supposing the contrary, we must presume that, subsequent to the primordial constitution of things, the Divine influence upon the world has been concurrent rather than revolutionizing. Hence a theory of origins, compatible with the simultaneous “creation” of primal organisms, is decidedly preferable to a theory, which involves successive “creations” at random. That transformism dispenses with the need of assuming a succession of “creative” acts, is perfectly obvious, and, unless fixism can emulate its rival system in this respect, it cannot expect to receive serious attention.

But once fixism assumes the simultaneousness of organic origins, it encounters, in the absence of modern organic types from ancient geological strata, a new and formidable difficulty. Cuvier’s theory of numerous catastrophes followed by wholesale migrations of the forms, which had escaped extinction, is tantamount to an appeal to the extraordinary and the improbable for purposes of explanation, and this, as we have seen, is an expedient, which natural science is justified in refusing to sanction. Nor does the appeal to the incompleteness of the geological record offer a more satisfactory solution. It is tax enough, as we shall see, upon our credulity, when the transformist seeks to account thereby for the absence of intermediate types, but to account in this fashion for the absence of palæozoic Angiosperms and mammals is asking us to believe the all-but-incredible. It would not, therefore, be advisable for the fixist to appropriate the line of defense suggested for him by Bateson—“It has been asked how do you know for instance that there were no mammals in Palæozoic times? May there not have been mammals somewhere on the earth though no vestige of them has come down to us? We may feel confident there were no mammals then, but are we sure? In very ancient rocks most of the great orders of animals are represented. The absence of the others might by no great stress of imagination be ascribed to accidental circumstances.” But the sudden rise of the Angiosperms in the early part of the Mesozoic era is an instance of de novo origin that is not so easily explained away. Hence Bateson continues: “Happily, however, there is one example of which we can be sure. There were no Angiosperms—that is to say ‘higher plants’ with protected seeds—in the carboniferous epoch. Of that age we have abundant remains of a worldwide and rich flora. The Angiosperms are cosmopolitan. By their means of dispersal they must immediately have become so. Their remains are very readily preserved. If they had been in existence on the earth in carboniferous times they must have been present with the carboniferous plants, and must have been preserved with them. Hence we may be sure that they did appear on earth since those times. We are not certain, using certain in the strict sense, that Angiosperms are the lineal descendants of the carboniferous plants, but it is much easier to believe that they are than that they are not.” (Science, Jan. 20, 1922, p. 58.)

It would thus appear, that not all the organic types of either the plant, or the animal, kingdom are of equal antiquity, and that the belated rise of unprecedented forms has the status of an approximate certainty, wherewith every theory of origins must inevitably reckon. How, then, is the fixist to reconcile this successive appearance of organisms with the simultaneous “creation” advocated by St. Augustine and St. Thomas of Aquin? Unless there be some other gradual process besides transmutation, to bridge the interval between the creative fiat and the eventual appearance of modern types, there seems to be no escape from the dilemma.

This brings us to St. Augustine’s theory of the evolution of organic life from inorganic matter, which Dorlodot sophistically construes as supporting the theory of descent. According to St. Augustine, for whose view the Angelic Doctor expressed a deliberate preference, the creation of the corporeal world was the result of a single creative act, having an immediate effect in the case of minerals, and a remote or postponed effect in the case of plants and animals (cf. “De Genesi ad litteram,” lib. V, c. 5). Living beings, therefore, were created, not in actuality, but in germ. God imparted to the elements the power of producing the various plants and animals in their proper time and place. Hence living beings were created causally rather than formally, by the establishment of causal mechanisms or natural agencies especially ordained to bring about the initial formation of the ancestral forms of life. The Divine act initiating these “natural processes” (rationes seminales, rationes causales) in inorganic, and not in living, matter, was instantaneous, but the processes, which terminated in the formation of plants and animals, in their appointed time and place, were in themselves gradual and successive. Thus by an influx of Divine power the earth was made pregnant with the promise of every form of life—“Sicut matres gravidae sunt foetibus, sic ipse mundus est gravidus causis nascentium.” (Augustine, lib. III, “de Trinitate,” c. 9.)

By reason of this doctrine, the Louvain professor claims that St. Augustine was an evolutionist, and so, indeed, he was, if by evolution is meant a gradual production of organisms from inorganic matter. But if, on the contrary, by evolution is meant a progressive differentiation and multiplication of organic species by transmutation of preëxistent forms of life, or, in other words, if evolution is taken in its usual sense as synonym for transformism, then nothing could be more absurdly anachronistic than to ascribe the doctrine to St. Augustine. The subject of the gradual process postulated by the latter was, not living, but inorganic, matter, and the process was conceived as leading to the formation, and not the transformation, of species. The idea of variable inheritance did not occur to St. Augustine, and he conceived organisms, once they were in existence, as being propagated exclusively by univocal reproduction (generatio univoca). It is the fixist, therefore, rather than the transformist, who is entitled to exploit the Augustinian hypothesis. In fact, it is only the vicious ambiguity and unlimited elasticity of the term evolution, which avail to extenuate the astounding confusion of ideas and total lack of historic sense, that can bracket together under a common term the ideology of Darwin and the view of St. Augustine.

§ 2. The Argument in the Concrete

But it is our task to criticize the theory of transformism, and not to throw a life-line to fixism, by advocating gradual formation of species as the only feasible alternative to gradual transformation of species. Perhaps, this particular life-line will not be appreciated any way; for the fixist may, not without reason, prefer to rest his case on the contention that the intrinsic time-value of geological formations is far too problematic for certain conclusions of any sort. In maintaining this position, he will have the support of some present-day geologists, and can point, as we shall see, to facts that seem to bear out his contention. In fact, the cogency of the palæontological argument appears to be at its maximum in the abstract, and to evaporate the moment we carry it into the concrete. The lute seems perfect, until we begin to play thereon, and then we discover certain rifts that mar the effect. It is to these rifts that our attention must now be turned.

The first and most obvious flaw, in the evolutionary interpretation of fossil series, is the confounding of succession with filiation. Thinkers, from time immemorial, have commented on the deep chasm of distinction, which divides historical from causal sequence, and philosophers have never ceased to inveigh against the sophistical snare of: Post hoc, ergo propter hoc. That one form of life has been subsequent in time to another form of life is, in itself, no proof of descent. “Let us suppose,” says Bather, “all written records to be swept away, and an attempt made to reconstruct English history from coins. We could set out our monarchs in true order, and we might suspect that the throne was hereditary; but if on that assumption we were to make James I, the son of Elizabeth—well, but that’s just what palæontologists are constantly doing. The famous diagram of the Evolution of the Horse which Huxley used in his American lectures has had to be corrected in the light of the fuller evidence recently tabulated in a handsome volume by Prof. H. F. Osborn and his coadjutors. Palæotherium, which Huxley regarded as a direct ancestor of the horse, is now held to be only a collateral, as the last of the Tudors were collateral ancestors of the Stuarts. The later Ancitherium must be eliminated from the true line as a side branch—a Young Pretender. Sometimes an apparent succession is due to immigration of a distant relative from some other region—‘The glorious House of Hanover and Protestant Succession.’ It was, you will remember, by such migrations that Cuvier explained the renewal of life when a previous fauna had become extinct. He admitted succession but not descent.” (Science, Sept. 17, 1920, p. 261.)

But, if succession does not imply descent, descent, at least, implies succession, and the fact that succession is the necessary corollary of descent, may be used as a corrective for the erroneous allocations made by neontologists on the basis of purely morphological considerations. The priority of a type is the sine qua non condition of its being accepted as ancestral. It is always embarrassing when, as sometimes happens, a “descendant” turns out to be older than, or even coëval with, his “ancestor.” If, however, the historical position of a form can be made to coincide with its anatomical pretensions to ancestry, then the inference of descent attains to a degree of logical respectability that is impossible in the case of purely zoölogical evidence. Recent years have witnessed a more drastic application of the historical test to morphological speculations, and the result has been a wholesale revision of former notions concerning phylogeny. “I could easily,” says Bather, “occupy the rest of this hour by discussing the profound changes wrought by this conception on our classification. It is not that orders and classes hitherto unknown have been discovered, not that some erroneous allocations have been corrected, but the whole basis of our system is being shifted. So long as we were dealing with a horizontal section across the tree of life—that is to say, with an assemblage of approximately contemporaneous forms—or even with a number of such horizontal sections, so long were we confined to simple description. Any attempt to frame a causal connection was bound to be speculative.” (Ibidem, p. 258.) Whether zoölogists will take kindly to this “shifting of the whole basis” of classification, remains to be seen. Personally, we think they would be very ill-advised to exchange the solid observational basis of homology for the scanty facts and fanciful interpretations of palæontologists.

The second stumbling block in the path of Transformism is the occurrence of convergence. We have seen that, in the palæontological argument, descent is inferred conjointly from similarity and succession, and that, in the abstract, this argument is very persuasive. One of the concrete phenomena, however, that tend to make it inconsequential, is the undoubted occurrence of convergence. Prof. H. Woods of Cambridge, in the Introduction to the 5th edition of his “Palæontology” (1919), speaks of three kinds of convergence (cf., pp. 14, 15, 16), which, as a matter of convenience, we may term the parallelistic, the radical, and the adaptational, types of convergence. A brief description of each type will serve to elucidate its nature and its significance:

(1) Parallelistic convergence implies the appearance of parallel modifications in the homologous parts of organisms regarded as diverging from common stock in two distinct collateral lines, that were independent at the time of the appearance in both of the said parallel modifications. Speaking of the fossil cœlenterates known as Graptolites, Professor Woods says: “In some genera the hydrothecæ of different species show great variety of form, those of one species being often much more like those of a species belonging to another genus than to other species of the same genus.” (“Palæontology,” 5th ed., 1919, p. 69.) As another instance of this phenomenon, the case of the fossil ungulates of South America, spoken of as Litopterna, may be cited, and the case is peculiarly interesting because of its bearing on that pièce de résistance of palæontological evidence, the Pedigree of the Horse. “The second family of Litopterna,” says Wm. B. Scott, “the Proterotheriidæ, were remarkable for their many deceptive resemblances to horses. Even though those who contend that the Litopterna should be included in the Perissodactyla should prove to be in the right, there can be no doubt that the proterotheres were not closely related to the horses, but formed a most striking illustration of the independent acquisition of similar characters through parallel or convergent development. The family was not represented in the Pleistocene, having died out before that epoch, and the latest known members of it lived in the upper Pliocene.... Not that this remarkable character was due to grotesque proportions; on the contrary, they looked far more like the ordinary ungulates of the northern hemisphere than did any of their South American contemporaries; it is precisely this resemblance that is so notable.... The feet were three-toed, except in one genus (Thoatherium) in which they were single-toed, and nearly or quite the whole weight was carried upon the median digit, the laterals being mere dew-claws. The shape of the hoofs and the whole appearance of the foot was surprisingly like those of the three-toed horses, but there were certain structural differences of such great importance, in my judgment, as to forbid the reference of these animals, not merely to the horses, but even to the perissodactyls.” (“A History of Land Mammals in the Western Hemisphere,” p. 499.)

For this sort of parallelism, the Lamarckian and Darwinian types of evolution by addition can offer no rational explanation. It could, perhaps, be accounted for upon the Batesonian hypothesis of evolution by loss of inhibition, that is to say, the coincident appearance of convergent characters in collateral lines might be interpreted as being due to a parallel loss in both lines of the inhibitive genes, which had suppressed the convergent feature in the primitive or common stock. We say that the convergence might be so interpreted, because the interpretation in question would, at best, be merely optional and not at all necessary; for in the third, or adaptational, type of convergence, we shall see instances of parallel modifications occurring in completely independent races, whose morphology and history alike exclude all possibility of hereditary connection between them. Hence, even in the present case, nothing constrains us to accept the genetic interpretation.

(2) Radical convergence, which Woods styles heterogenetic homœomorphy, is described by him as follows: “Sometimes two groups of individuals resemble each other so closely that they might be regarded as belonging to the same genus or even to the same species (italics mine), but they have descended from different ancestors since they are found to differ in development (ontogeny) or in their palæontological history; this phenomenon, of forms belonging to different stocks approaching one another in character, is known as convergence or heterogenetic homœomorphy, and may occur at the same geological period or at widely separated intervals. Thus the form of oyster known as Gryphaea has originated independently from oysters of the ordinary type in the Lias, in the Oölites, and again in the Chalk; these forms found at different horizons closely resemble one another and have usually been regarded as belonging to one genus (Gryphaea), but they have no direct genetic connection with one another.” (“Palæontology,” 5th ed., 1919, p. 15.) Comment is almost superfluous. If even specific resemblance is no proof of common origin, then what right have we to interpret any resemblance whatever in this sense? With such an admission, the whole bottom drops out of the evolutionary argument. When the theory of descent is forced to account for heterogenetic resemblance at expense of all likelihood and consistency, when it cannot save itself except by blowing hot and cold with one breath, one is tempted to exclaim: “Oh, why bother with it!”

(3) Adaptational convergence is the occurrence of parallel modifications due to analogous specialization in unrelated forms, whose phylogeny has been obviously diverse. “Also, animals belonging to quite distinct groups,” says Woods, “may, when living under similar conditions, come to resemble one another owing to the development of adaptive modifications, though they do not really approach one another in essential characters; thus analogous or parallel modifications may occur in independent groups—such are the resemblances between flying reptiles (Ornithosaurs) and birds, and between sharks, icthyosaurs and dolphins.” (Op. cit., p. 16.) As this type of convergence has been discussed in a previous article, with reference to the mole and mole-cricket, it need not detain us further.

All these types of convergence, but especially the second type, are factual evidence of the compatibility of resemblance with independent origin, and the fact of their occurrence tends to undermine the certainty of the phylogenetic inferences based on fossil evidence; all the more so, that, thanks to its bad state of preservation, and the impossibility of dissection, even superficial resemblances may give rise to false interpretations. And, as for the cases of radical convergence, there is no denying that they strike at the very heart of the theory of descent.

The third difficulty for Transformism arises from the discontinuity of the geological record. It was one of the very first discrepancies to be discovered between evolutionary expectation and the actual results of research. The earliest explorations revealed a state of affairs, that subsequent investigations have failed to remedy: on the one hand, namely, a notable absence of intermediate species to bridge the gaps between the fossil genera, and on the other hand, the sudden and simultaneous appearance of numerous new and allied types unheralded by transitional forms. Since Darwin had stressed the gradualness of transmutation, the investigators expected to find the transitional means more numerous than the terminal extremes, and were surprised to find, in the real record of the past, the exact reverse of their anticipation. They found that the classes and families of animals and plants had always been as widely separated and as sharply differentiated as they are today, and that they had always formed distinct systems, unconnected by transitional links. The hypothetical “generalized types,” supposed to combine the features of two or three families, have never been found, and most probably never will be; for it is all but certain that they never existed. Occasionally, it is true, palæontologists have discovered isolated types, which they interpreted as annectant forms, but a single pier does not make a bridge, and only too often it chanced that the so-called annectant type, though satisfactory from the morphological standpoint, was more recent than the two groups, to which it was supposed to be ancestral. But it will make matters plainer, if we illustrate what is meant by the discontinuity or incompleteness of the fossil record, by reference to some concrete series, such as the so-called Pedigree of the Horse.

Whenever a series of fossils, arranged in the order of their historical sequence, exhibits a gradation of increasing resemblance to the latest form, with which the series terminates, such a series is called a palæontological pedigree, and is said to represent so many stages in the racial development or phylogeny of the respective modern type. The classical example of this sort of “pedigree” is that of the Horse. It is, perhaps, one of the most complete among fossil “genealogies,” and yet, as has been frequently pointed out, it is, as it stands, extremely incomplete. Modern representatives of the Equidae, namely, the horse, the ass and the zebra, belong to a common genus, and are separated from one another by differences which are merely specific, but the differences which separate the various forms, that compose the “pedigree of the Horse,” are generic. We have, to borrow Gerard’s simile, nothing more than the piers of the evolutionary bridge, without the arches, and we do not know whether there ever were any arches. There is, indeed, a sort of progression, e.g., from the four-toed to a one-toed type, so that the morphological gradation does, in some degree, coincide with temporal succession. But, on the other hand, the fossil forms, interpreted as stages in the phylogeny of the Horse, are separated from one another by gaps so enormous, that, in the absence of intermediate species to bridge the intervals, it is practically impossible, particularly in the light of our experimental knowledge of Genetics, to conceive of any transition between them. Nor is this all. The difficulty is increased tenfold, when we attempt to relate the Equidae to other mammalian groups. Fossil ungulates appear suddenly and contemporaneously in the Tertiary of North America, South America and Europe, without any transitional precursors, to connect them with the hypothetical proto-mammalian stock, and to substantiate their collaterality with other mammalian stocks.

To all such difficulties the evolutionist replies by alleging the incompleteness of the geological record, and modern handbooks on palæontology devote many pages to the task of explaining why incompleteness of the fossil record is just what we should expect, especially in the case of terrestrial animals. The reasons which they assign are convincing, but this particular mode of solving the difficulty is a rather precarious one. Evolutionists should not forget that, in sacrificing the substantial completeness of the record to account for the absence of intermediate species, they are simultaneously destroying its value as a proof of the relative position of organic types in time. Yet this, as we have seen, is precisely the feature of greatest strategic value in the palæontological “evidence” for evolution. We must have absolute certainty that the reputed “ancestor” was in existence prior to the appearance of the alleged “descendant,” or the peculiar force of the palæontological argument is lost. It would be preposterous for the progeny to be prior to, or even coëval with, the progenitor, and so we must be quite sure that what we call “posterity” is really posterior in time. Now the sole argument that palæontology can adduce for the posteriority of one organic type as compared with another is the negative evidence of its non-occurrence, or rather of its non-discovery, in an earlier geological formation. The lower strata do not, so far as is known, contain the type in question, and so it is concluded that this particular form had no earlier history. Such an inference, as is clear, is not only liable to be upset by later discoveries, but has the additional disadvantage of implicitly assuming the substantial completeness of the fossil record, whereas the absence of intermediate species is only explicable by means of the assumed incompleteness of the selfsame record. The evolutionist is thus placed in the dilemma of choosing between a substantially complete, and a substantially incomplete, record. Which of the alternatives, he elects, matters very little; but he must abide by the consequences of his decision, he cannot eat his cake and have it.

When the evolutionist appeals to the facts of palæontology, it goes without saying that he does so in the hope of showing that the differences, which divide modern species of plants and animals, diminish as we go backward in time, until the stage of identity is reached in the unity of a common ancestral type. Hence from the very nature of the argument, which he is engaged in constructing, he is compelled to resort to intermediate types as evidence of the continuity of allied species with the hypothetical ancestor, or common type, whence they are said to have diverged. Now, even supposing that his efforts in this direction were attended with a complete measure of success, evidence of this kind would not of itself, as we shall see, suffice to demonstrate the common origin of the extremes, between which a perfect series of intergradent types can be shown to mediate. Unquestionably, however, unless such a series of intergradent fossil species can be adduced as evidence of the assumed transition, the presumption is totally against the hypothesis of transformism.

Now, as a matter of fact, the geological record rarely offers any evidence of the existence in the past of intermediate species. For those, who have implicit confidence in the time-value of geological “formations,” there are indications of a general advance from lower to higher forms, but, even so, there is little to show that this seeming progress is to be interpreted as an increasing divergence from common ancestral types. With but few exceptions, the fossil record fails to show any trace of transitional links. Yet pedigrees made up of diverse genera are poor evidence for filiation or genetic continuity, so long as no intermediate species can be found to bridge the chasm of generic difference. By intermediate species, we do not mean the fabulous “generalized type.” Annectants of this kind are mere abstractions, which have never existed, and never could have existed. We refer rather to actual fossil types separated from one another by differences not greater than specific; for “not until we have linked species into lineages,” can fossil pedigrees lay claim to serious attention.

But let us suppose the case for evolution to be ideally favorable, and assume that in every instance we possessed a perfect gradation of forms between two extremes, such, for example, as occurs in the Ammonite series, even then we would be far from having a true demonstration of the point at issue. Bateson has called our attention to the danger of confounding sterile and instable hybrids with intergradent species. “Examine,” he says, “any two thoroughly distinct species which meet each other in their distribution, as for instance, Lychnis diurna and vespertina do. In areas of overlap are many intermediate forms. These used to be taken to be transitional steps, and the specific distinctness of vespertina and diurna was on that account questioned. Once it is known that these supposed intergrades are merely mongrels between the two species the transition from one to the other is practically beyond our powers of imagination to conceive. If both these can survive, why has their common parent perished? Why, when they cross, do they not reconstruct it instead of producing partially sterile hybrids? I take this example to show how entirely the facts were formerly misrepresented.” (Heredity, Smithson. Inst. Rpt. for 1915, p. 369.)

Similarly, T. H. Morgan has shown, with reference to mutants, the fallacy of inferring common descent from the phenomenon of intergradence, and what holds true for a series of intergradent mutants would presumably also hold true of a series of intergradent species, could such a series be found and critically distinguished from hybrid and mutational intermediates. In short, the Darwinian deduction of common origin from the existence of intergradence must now be regarded as a thoroughly discredited argument. “Because we can often arrange the series of structures in a line extending from the very simple to the more complex, we are apt to become unduly impressed by this fact and conclude that if we found the complete series we should find all the intermediate steps and that they have arisen in the order of their complexity. This conclusion is not necessarily correct.” (“A Critique of the Theory of Evolution,” p. 9.) Having cited such a series of gradational mutations ranging between the long-winged, and completely wingless condition, in the case of the Vinegar Fly (Drosophila melanogaster), as well as two similar graded series based on pigmentation and eye color, he concludes: “These types, with the fluctuations that occur within each type, furnish a complete series of gradations; yet historically they have arisen independently of each other. Many changes in eye color have appeared. As many as thirty or more races differing in eye color are now maintained in our cultures. Some of them are so similar that they can scarcely be separated from each other. It is easily possible beginning with the darkest eye color, sepia, which is a deep brown, to pick out a perfectly graded series ending with pure white eyes. But such a serial arrangement would give a totally false idea of the way the different types have arisen; and any conclusion based on the existence of such a series might very well be entirely erroneous, for the fact that such a series exists bears no relation to the order in which its members have appeared.” (Op. cit., pp. 12, 13.) Such facts must give us pause in attaching undue importance to phenomena like the occurrence of a gradual complication of sutures in the Chalk Ammonites, particularly as parallel series of perfectly similar sutures occurs “by convergence” in the fossil Ceratites, which have no genetic connection with the Ammonites. (Cf. Woods’ “Palæontology,” 5th ed., p. 16.)

But, if even mutational and specific intergradents are not sufficient evidence of common ancestry, what shall we say of a discontinuous series, whose links are separate genera, orders, or even classes, instead of species. Even the most enthusiastic transformist is forced to admit the justice of our insistence that the gaps which separate the members of a series must be reduced from differences of the generic, to differences of the specific, order, before that series can command any respect as hypothetical “genealogy.” “You will have observed,” says F. A. Bather, “that the precise methods of the modern palæontologist, on which this proof is based, are very different from the slap-dash conclusions of forty years ago. The discovery of Archæopteryx, for instance, was thought to prove the evolution of birds from reptiles. No doubt it rendered that conclusion extremely probable, especially if the major promise—that evolution was the method—were assumed. But the fact of evolution is precisely what men were then trying to prove. These jumpings from class to class or from era to era, by aid of a few isolated stepping-stones, were what Bacon calls anticipations “hasty and premature but very effective, because as they are collected from a few instances, and mostly from those which are of familiar occurrence, they immediately dazzle the intellect and fill the imagination.” (Nov. Org., I, 28.) No secure step was taken until the modern palæontologist began to affiliate mutation with mutation and species with species, working his way back, literally inch by inch, through a single small group of strata. Only thus could he base on the laboriously collected facts a single true interpretation; and to those who preferred the broad path of generality his interpretations seemed, as Bacon says they always “must seem, harsh and discordant—almost like mysteries of faith.” ... Thus by degrees we reject the old slippery stepping-stones that so often toppled us into the stream, and, foot by foot, we build a secure bridge over the waters of ignorance.” (Science, Sept. 17, 1920, pp. 263, 264.)

We cannot share Bather’s confidence in the security of a bridge composed of even linked species. Let such a series be never so perfect, let the gradation be never so minute, as it might conceivably be made, when not merely distinct species, but also hybrids, mutants and fluctuants are available as stopgaps, the bare fact of such intergradation tells nothing whatever concerning the problem of genetical origin and specific relationship. The species-by-species method does, however, represent the very minimum of requirement imposed upon the palæontologist, who professes to construct a fossil pedigree. But, when all is said and done, such a method, even at its best, falls considerably short of the mark. However perfectly intergradent a series of fossils may be, the fact remains that these petrified remnants of former life cannot be subjected to breeding tests, and that, in the consequent absence of genetical experimentation, we have no means of determining the real bearing of these facts upon the problem of interspecific relationship. Only the somatic characters of extinct floras and faunas have been conserved in the rock record of the past, and even these are often rendered dubious, as we shall see presently, by their imperfect state of preservation. Now, it is solely in conjunction with breeding experiments, that somatic characters can give us any insight into the nature of the germinal constitution of an organism, which, after all, is the cardinal consideration upon which the whole question of interspecific relationship hinges. All inferences, therefore, regarding the descent of fossil forms are irremediably speculative and conjectural. When we are dealing with living forms, we can always check up the inferences based on somatic characteristics by means of genetical experiments, and in so doing we have found that it is as unsafe to judge of an organism from the exclusive standpoint of its external characters as it is to judge of a book by the cover; for, apart from the check of breeding tests, it is impossible to say just which somatic characters are genetically significant, and which are not. Forms externally alike may be so unlike in germinal constitution as to be sexually incompatible; forms externally unlike may be readily crossed without any discernible diminution of fertility. “Who could have foreseen,” exclaims Bateson, “that the apple and the pear—so like each other that their botanical differences are evasive—could not be crossed together, though species of Antirrhinum (Snapdragon) so totally unlike each other as majus and molle can be hybridized, as Baur has shown, without a sign of impaired fertility?” (Heredity, Smithson. Inst. Rpt. for 1915, p. 370.) We cannot distinguish between alleged specific, and merely mutational (varietal), change, nor between hybridizations and factorial, chromosomal, or pseudo-, mutations, solely on the basis of such external characters as are preserved for us in fossils. It is impossible, therefore, to demonstrate trans-specific variation by any evidence that Palæontology can supply. The palæontologist (pace Osborn) is utterly incompetent to pass judgment on the problem of interspecific relationship. As Bateson remarks: “In discussing the physiological problem of interspecific relationship evidence of a more stringent character is now required; and a naturalist acquainted with genetical discoveries would be as reluctant to draw conclusions as to the specific relationship of a series of fossils as a chemist would be to pronounce on the nature of a series of unknown compounds from an inspection of them in a row of bottles.” (Science, April 17, 1922, p. 373.) “When the modern student of variation and heredity,” says T. H. Morgan, “looks over the different ‘continuous’ series, from which certain ‘laws’ and ‘principles’ have been deduced, he is struck by two facts: that the gaps, in some cases, are enormous as compared with the single changes with which he is familiar, and (what is more important) that they involve numerous parts in many ways. The geneticist says to the palæontologist, since you do not know, and from the nature of your case can never know, whether your differences are due to one change or to a thousand, you cannot with certainty tell us anything about the hereditary units which have made the process of evolution possible.” (Op. cit., pp. 26, 27.) And without accurate knowledge on this subject, we may add, there is no possibility of demonstrating specific change or genetic relationship in the case of any given fossil.

In our discussion of the third defect in the fossil “evidence,” allusion was made to a fourth, namely, its imperfect state of preservation. The stone record of bygone days has been so defaced by the metamorphism of rocks, by the solvent action of percolating waters, by erosion, weathering and other factors of destruction, that, like a faded manuscript, it becomes, even apart from its actual lacunae, exceedingly difficult to decipher. So unsatisfactory, indeed, is the condition of the partially obliterated facts that human curiosity, piqued at their baffling ambiguity, calls upon human imagination to supply what observation itself fails to reveal. Nor does the invitation remain unheeded. Romance hastens to the rescue of uncertain Science, with an impressive display of “reconstructed fossils,” and the hesitation of critical caution is superseded by the dogmatism of arbitrary assumption. Scattered fragments of fossilized bones are integrated into skeletons and clothed by the magic of creative fancy with an appropriate musculature and flesh, reënacting for us the marvelous vision of Ezekiel: “And the bones came together, each one to its joint. And I beheld and, lo, there were sinews upon them, and the flesh came upon them: and the skin was stretched over them.” (Chap. XXXVII, 7, 8.) “It is also true,” says Osborn (who, like Haeckel, evinces a veritable mania for “retouching” incomplete facts), “that we know the mode of origin of the human species; our knowledge of human evolution has reached a point not only where a number of links are thoroughly known but the characters of the missing links can be very clearly predicated.” (Science, Feb. 24, 1922.) We will not dispute his contention; for it is perfectly true, that, in each and every case, all the missing details can be so exactly predicated that the resulting description might well put to shame the account of a contemporary eyewitness. The only difficulty is that such predication is the fruit of pure imagination. Scientific reconstructions, whether in the literary, plastic, or pictorial, form, are no more scientific than historical novels are historical. Both are the outcome of a psychological weakness in the human makeup, namely, its craving for a “finished picture”—a craving, however, that is never gratified save at the expense of the fragmentary basis of objective fact.[7]

In calling into question, however, the scientific value of the so-called “scientific reconstruction,” so far as its pretensions to precision and finality are concerned, it is not our intention to discredit those tentative restorations based upon Cuvier’s Law of Correlation, provided they profess to be no more than provisional approximations. Many of the structural features of organisms are physiologically interdependent, and there is frequently a close correlation among organs and organ-systems, between which no causal connection or direct physiological dependence is demonstrable. In virtue of this principle, one structural feature may connote another, in which case it would be legitimate to supply by inference any missing structure implied in the actual existence of its respective correlative. But if any one imagines that the law of correlation enables a scientist to restore the lost integrity of fossil types with any considerable degree of accuracy and finality, he greatly overestimates the scope of the principle in question. At best it is nothing more than an empirical generalization, which must not be pressed to an extent unwarranted by the inductive process, that first established it. “Certain relations of structure,” says Bather, “as of cloven hoofs and horns with a ruminant stomach, were observed, but as Cuvier himself insisted, the laws based on such facts were purely empirical.” (Science, Sept. 17, 1920, p. 258.) The palæontologist, then, is justified in making use of correlation for the purpose of reconstructing a whole animal out of a few fragmentary remains, but to look for anything like photographic precision in such “restorations” of extinct forms is to manifest a more or less complete ignorance of the nature and scope of the empirical laws, upon which they are based.

The imprudence of taking these “reconstructions” of extinct forms too seriously, however, is inculcated not merely by theoretical considerations, but by experience as well. Even in the case of the mammoth, a comparatively recent form, whose skeletal remains had been preserved more completely and perfectly than those of other fossil types, the discovery of a complete carcass buried in the ice of the Siberian “taiga” on the Beresovka river showed the existing restorations to be false in important respects. All, without exception, stood in need of revision, proving, once and for all, the inadequacy of fossil remains as a basis for exact reconstruction. E. Pfizenmayer, a member of the investigating expedition, comments on the fact as follows: “In the light of our present knowledge of the mammoth, and especially of its exterior, the various existing attempts at a restoration need important corrections. Apart from the many fanciful sketches intended to portray the exterior of the animal, all the more carefully made restorations show the faults of the skeleton, hitherto regarded as typical, on which they are based, especially the powerful semicircular and upward-curved tusks, the long tail, etc.

“As these false conceptions of the exterior of the mammoth, both written and in the form of pictures, are contained in all zoölogical and palæontological textbooks, and even in scientific monographs, it seems necessary to construct a more nearly correct picture, based on our present knowledge. I have ventured on this task, because as a member of the latest expedition for mammoth remains, I was permitted not only to become acquainted with this newest find while still in its place of deposit and to take part in exhuming it, but also to visit the zoölogical museum of St. Petersburg, which is so rich in mammoth remains, for the purpose of studying the animal more in detail.” (Smithson. Inst. Rpt. for 1906, pp. 321, 322.) The example is but one of many, which serve to emphasize not merely the inadequacy of the generality of palæontological restorations, but also the extreme difficulty which the palæontologist experiences in interpreting aright the partially effaced record of a vanished past.

The fifth and most critical flaw in the fossil “evidence” for evolution is to be found in the anomalies of the actual distribution of fossils in time. It is the boast of evolutionary Palæontology that it is able to enhance the cogency of the argument from mere structural resemblance by showing, that, of two structurally allied forms, one is more ancient than the other, and may, therefore, be presumed to be ancestral to the later form. Antecedence in time is the sine qua non qualification of a credible ancestor, and, unless the relative priority of certain organic types, as compared with others, can be established with absolute certainty, the whole palæontological argument collapses, and the boast of evolutionary geology becomes an empty vaunt.

Whenever the appearance of a so-called annectant type is antedated by that of the two forms, which it is supposed to connect, this fact is, naturally, a deathblow to its claim of being the “common ancestor,” even though, from a purely morphological standpoint, it should possess all the requisites of an ancestral type. Commenting upon the statement that a certain genus “is a truly annectant form uniting the Melocrinidae and the Platycrinidae,” Bather takes exception as follows: “The genus in question appeared, so far as we know, rather late in the Lower Carboniferous, whereas both Platycrinidae and Melocrinidae were already established in Middle Silurian time. How is it possible that the far later form should unite these two ancient families? Even a mésalliance is inconceivable.” (Science, Sept. 17, 1920, p. 260.)

Certainty, therefore, with respect to the comparative antiquity of the fossiliferous strata is the indispensable presupposition of any palæontological argument attempting to show that there is a gradual approximation of ancient, to modern, types. Yet, of all scientific methods of reckoning, none is less calculated to inspire confidence, none less safeguarded from the abuses of subjectivism and arbitrary interpretation, than that by which the relative age of the sedimentary rocks is determined!

In order to date the strata of any given series with reference to one another, the palæontologist starts with the principle that, in an undisturbed area, the deeper sediments have been deposited at an earlier period than the overlying strata. Such a criterion, however, is obviously restricted in its application to local areas, and is available only at regions of outcrop, where a vertical section of the strata is visibly exposed. To trace the physical continuity, however, of the strata (if such continuity there be) from one continent to another, or even across a single continent, is evidently out of the question. Hence, to correlate the sedimentary rocks of a given region with those of another region far distant from the former, some criterion other than stratigraphy is required. To supply this want, recourse has been had to index fossils, which have now come into general use as age-markers and means of stratigraphical correlation, where the criterion of superposition is either absent or inapplicable. Certain fossil types are assumed to be infallibly indicative of certain stratigraphical horizons. In fact, when it comes to a decision as to the priority or posteriority of a given geological formation, index fossils constitute the court of last appeal, and even the evidences of actual stratigraphical sequence and of physical texture itself are always discounted and explained away, whenever they chance to conflict with the presumption that certain fossil forms are typical of certain geological periods. If, for example, the superposed rock contains fossils alleged to be typical of an “earlier” stratigraphic horizon than that to which the fossils of the subjacent rock belong, the former is pronounced to be “older,” despite the fact that the actual stratigraphic order conveys the opposite impression. “We still regard fossils,” says J. W. Judd, “as the ‘medals of creation,’ and certain types of life we take to be as truly characteristic of definite periods as the coins which bear the image and superscription of a Roman emperor or of a Saxon king.” (Cf. Smithson. Inst. Rpt. for 1912, p. 356.) Thus it comes to pass, in the last analysis, that fossils, on the one hand, are dated according to the consecutive strata, in which they occur, and strata, on the other hand, are dated according to the fossils which they contain.

Such procedure, if not actually tantamount to a vicious circle, is, to say the least, in imminent danger of becoming so. For, even assuming the so-called empirical generalization, that makes certain fossils typical of certain definitely-aged geological “formations,” to be based upon induction sufficiently complete and analytic to insure certainty, at least, in the majority of instances, and taking it for granted that we are dealing with a case, where the actual evidence of stratigraphy is not in open conflict with that of the index fossils, who does not see that such a system of chronology lends itself only too readily to manipulation of the most arbitrary kind, whenever the pet preconceptions of the evolutionary chronologist are at stake? How, then, can we be sure, in a given case, that a verdict based exclusively on the “evidence” of index fossils will be reliably objective? It is to be expected that the evolutionist will refrain from the temptation to give himself the benefit of every doubt? Will there not be an almost irresistible tendency on the part of the convinced transformist to revise the age of any deposit, which happens to contain fossils that, according to his theory, ought not to occur at the time hitherto assigned?

The citation of a concrete example will serve to make our meaning clear. A series of fresh-water strata occur in India known as the Siwalik beds. The formation in question was originally classed as Miocene. Later on, however, as a result, presumably, of the embarrassing discovery of the genus Equus among the fossils of the Upper Siwalik beds, Wm. Blanford saw fit to mend matters by distinguishing the Upper, from the Lower, beds and assigning the former (which contain fossil horses) to the Pliocene period. The title Miocene being restricted by this ingenious step to beds destitute of equine remains, namely the Nahun, or Lower Siwalik, deposits, all danger of the horse proving to be older than his ancestors was happily averted. A mere shifting of the conventional labels, apparently, was amply sufficient to render groundless the fear, to which Professor A. Sedgwick had given expression in the following terms: “The genus Equus appears in the upper Siwalik beds, which have been ascribed to the Miocene age.... If Equus really existed in the Upper Miocene, it was antecedent to some of its supposed ancestors.” (“Students’ Textbook of Zoölogy,” p. 599.) Evidently, the Horse must reconcile himself perforce to the pedigree assigned to him by the American Museum of Natural History; for he is to be given but scant opportunity of escaping it. This classic genealogy has already entailed far too great an expenditure of time, money and erudition to permit of any reconsideration; and should it chance, in the ironic perversity of things, that the Horse has been so inconsiderate as to leave indubitable traces of himself in any formation earlier than the Pliocene, it goes without saying that the formation in question will at once be dated ahead, in order to secure for the “ancestors” that priority which is their due. An elastic criterion like the index fossil is admirably adapted for readjustments of this sort, and the evolutionist who uses it need never fear defeat. The game he plays can never be a losing one, because he gives no other terms than: Heads I win, tails you lose.

In setting forth the foregoing difficulties, we have purposely refrained from challenging the cardinal dogma of orthodox palæontology concerning the unimpeachable time-value of index fossils as age-markers. The force of these considerations, therefore, must be acknowledged even by the most fanatical adherents of the aforesaid dogma. Our forbearance in this instance, however, must not be construed as a confession that the dogma in question is really unassailable. On the contrary, not only is it not invulnerable, but there are many and weighty reasons for rejecting it lock, stock, and barrel.

The palæontological dogma, to which we refer, is reducible to the following tenets: (1) The earth is swathed with fossiliferous strata, in much the same fashion that an onion is covered with a succession of coats, and these strata are universal over the whole globe, occurring always in the same invariable order and characterized not by any peculiar uniformity of external appearance, physical texture, or mineral composition, but solely by peculiar groups of fossil types, which enable us to distinguish between strata of different ages and to correlate the strata of one continent with their counterparts in another continent—“Even the minuter divisions,” says Scott, “the substages and zones of the European Jura, are applicable to the classification of the South American beds.” (“Introduction to Geology,” p. 681.) (2) In determining the relative age of a given geological formation, its characteristic fossils form the exclusive basis of decision, and all other considerations, whether lithological or stratigraphic, are subordinated to this—“The character of the rocks,” says H. S. Williams, “their composition or their mineral contents have nothing to do with settling the question as to the particular system to which the new rocks belong. The fossils alone are the means of correlation.” (“Geological Biology,” pp. 37, 38.)

To those habituated to the common notion that stratigraphical sequence is the foremost consideration in deciding the comparative age of rocks, the following statement of Sir Archibald Geikie will come as a distinct shock: “We may even demonstrate,” he avers, “that in some mountainous ground the strata have been turned completely upside down, if we can show that the fossils in what are now the uppermost layers ought properly to lie underneath those in the beds below them.” (“Textbook,” ed. of 1903, p. 837.) In fact, the palæontologist, H. A. Nicholson, lays it down as a general principle that, wherever the physical evidence (founded on stratigraphy and lithology) is at variance with the biological evidence (founded on the presence of typical fossil organisms), the latter must prevail and the former must be ignored: “It may even be said,” he tells us, “that in any case where there should appear to be a clear and decisive discordance between the physical and the palæontological evidence as to the age of a given series of beds, it is the former that is to be distrusted rather than the latter.” (“Ancient Life History of the Earth,” p. 40.)

George McCready Price, Professor of Geology at a denominational college in Kansas, devotes more than fifty pages of his recent work, “The New Geology” (1923), to an intensely destructive criticism of this dogma of the supremacy of fossil evidence as a means of determining the relative age of strata. To cite Price as an “authority” would, of course, be futile. All orthodox geologists have long since anathematized him, and outlawed him from respectable geological society. Charles Schuchert of Yale refers to him as “a fundamentalist harboring a geological nightmare.” (Science, May 30, 1924, p. 487.) Arthur M. Miller of Kentucky University speaks of him as “the man who, while a member of no scientific body and absolutely unknown in scientific circles, has ... had the effrontery to style himself a ‘geologist.’” (Science, June 30, 1922, pp. 702, 703.) Miller, however, is just enough to admit that he is well-informed on his subject, and that he possesses the gift of persuasive presentation. “He shows,” says Miller, “a wide familiarity with geological literature, quoting largely from the most eminent authorities in this country and in Europe. Any one reading these writings of Price, which possess a certain charm of literary style, and indicate on the part of the author a gift of popular presentation which makes one regret that it had not been devoted to a more laudable purpose, must constantly marvel at the character of mind of the man who can so go into the literature of the subject and still continue to hold such preposterous opinions.” (Loc. cit., p. 702.)

In the present instance, however, our interest centers, not on the unimportant question of his official status in geological circles, but exclusively on the objective validity of his argument against the chronometric value of the index fossil. All citations, therefore, from his work will be supported, in the sequel, by collateral testimony from other authors of recognized standing. It is possible, of course, to inject irrelevant issues. Price, for example, follows Sir Henry Howorth in his endeavor to substitute an aqueous catastrophe for the glaciation of the Quaternary Ice Age, and he adduces many interesting facts to justify his preference for a deluge. But this is neither here nor there; for we are not concerned with the merits of his “new catastrophism.” It is his opportune revival in modern form of the forgotten, but extremely effective, objection raised by Huxley and Spencer against the alleged universality of synchronously deposited fossiliferous sediments, that constitutes our sole preoccupation here. It is Price’s merit to have shown that, in the light of recently discovered facts, such as “deceptive conformities” and “overthrusts,” this objection is far graver than it was when first formulated by the authors in question.

Mere snobbery and abuse is not a sufficient answer to a difficulty of this nature, and we regret that men, like Schuchert, have replied with more anger than logic. The orthodox geologist seems unnecessarily petulant, whenever he is called upon to verify or substantiate the foundational principles of lithic chronology. One frequently hears him make the excuse that “geology has its own peculiar method of proof.” To claim exemption, however, from the universal criterions of criticism and logic is a subterfuge wholly unworthy of a genuine science, and, if Price insists on discussing a subject, which the orthodox geologist prefers to suppress, it is the latter, and not the former, who is really reactionary.

Price begins by stating the issue in the form of a twofold question: (1) How can we be sure, with respect to a given fauna (or flora), say the Cambrian, that at one time it monopolized our globe to the complete exclusion of all other typical faunas (or floras), say the Devonian, or the Tertiary, of which it is assumed that they could not, by any stretch of imagination, have been contemporaneous, on either land or sea, with the aforesaid “older” fauna (or flora)? (2) Do the formations (rocks containing fossils) universally occur in such a rigidly invariable order of sequence with respect to one another, as to warrant our being sure of the starting-point in the time-scale, or to justify us in projecting any given local order of succession into distant localities, for purposes of chronological correlation?

His response to the first of these questions constitutes what may be called an aprioristic refutation of the orthodox view, by placing the evolutionary palæontologist in the trilemma: (a) of making the awkward confession that, except within limited local areas, he has no means whatever of distinguishing between a geographical distribution of coëval fossil forms among various habitats and a chronological distribution of fossils among sediments deposited at different times; (b) or of denying the possibility of geographical distribution in the past, by claiming dogmatically that the world during Cambrian times, for example, was totally unlike the modern world, of which alone we have experimental knowledge, inasmuch as it was then destitute of zoölogical provinces, districts, zones, and other habitats peculiar to various types of fauna, so that the whole world formed but one grand habitat, extending over land and sea, for a limited group of organisms made up exclusively of the lower types of life; (c) or of reviving the discredited onion-coat theory of Abraham Werner under a revised biological form, which asserts that the whole globe is enveloped with fossiliferous rather than mineral strata, whose order of succession being everywhere the same enables us to discriminate with precision and certainty between cases of distribution in time and cases of distribution in space.

In his response to the second question, Professor Price adduces numerous factual arguments, which show that the invariable order of sequence postulated by the theory of the time-value of index fossils, not only finds no confirmation in the actual or concrete sequences of fossiliferous rocks, but is often directly contradicted thereby. “Older” rocks may occur above “younger” rocks, the “youngest” may occur in immediate succession to the “oldest,” Tertiary rocks may be crystalline, consolidated, and “old in appearance,” while Cambrian and even pre-Cambrian rocks sometimes occur in a soft, incoherent condition, that gives them the physical appearance of being as young as Pleistocene formations. These exceptions and objections to the “invariable order” of the fossiliferous strata accumulate from day to day, and it is only by means of Procrustean tactics of the most drastic sort that the facts can be brought into any semblance of harmony with the current dogmas, which base geology upon evolution rather than evolution upon geology.

Price, then, proposes for serious consideration the possibility that Cretaceous dinosaurs and even Tertiary mammals may have been living on the land at the same time that the Cambrian graptolites and trilobites were living in the seas. “Who,” he exclaims, “will have the hardihood, the real dogmatism to affirm in a serious way that Cambrian animals and seaweeds were for a long time the only forms of life existing anywhere on earth?” Should we, nevertheless, make bold enough to aver that for countless centuries a mere few of the lower forms of life monopolized our globe, as one universal habitat unpartitioned into particular biological provinces or zones, we are thereupon confronted with two equally unwelcome alternatives. We must either fly in the face of experience and legitimate induction by denying the existence in the past of anything analogous to our present-day geographical distribution of plants and animals into various biological provinces, or be prepared to show by what infallible criterion we are enabled to distinguish between synchronously deposited formations indicative of a geographical distribution according to regional diversity, and consecutively deposited formations indicative of comparative antiquity.

The former alternative does not merit any consideration whatever. The latter, as we shall presently see, involves us in an assumption, for which no defense either aprioristic or factual is available. We can, indeed, distinguish between spatial, and temporal, distribution within the narrow limits of a single locality by using the criterion of superposition; for in regions of outcrop, where one sedimentary rock overlies another, the obvious presumption is that the upper rock was deposited at a later date than the lower rock. But the criterion of superposition is not available for the correlation of strata in localities so distant from each other that no physical evidence of stratigraphic continuity is discernible. Moreover the induction, which projects any local order of stratigraphical sequence into far distant localities on the sole basis of fossil taxonomy, is logically unsound and leads to conclusions at variance with the actual facts. Hence the alleged time-value of index fossils becomes essentially problematic, and affords no basis whatever for scientific certainty.

As previously stated, the sequence of strata is visible only in regions of outcrop, and nowhere are we able to see more than mere parts of two or, at most, three systems associated together in a single locality. Moreover, each set of beds is of limited areal extent, and the limits are frequently visible to the eye of the observer. In any case, their visible extent is necessarily limited. It is impossible, therefore, to correlate the strata of one continent with those of another continent by tracing stratigraphic continuity. Hence, in comparing particular horizons of various ages and in distinguishing them from other horizons over large areas, we are obliged to substitute induction for direct observation. Scientific induction, however, is only valid when it rests upon some universal uniformity or invariable sequence of nature. Hence, to be specific, the assumption that the time-scale based on the European classification of fossiliferous strata is applicable to the entire globe as a whole, is based on the further assumption that we are sure of the universality of fossiliferous stratification over the face of the earth, and that, as a matter of fact, fossils are always and everywhere found in the same order of invariable sequence.

But this is tantamount to reviving, under what Spencer calls “a transcendental form,” the exploded “onion-coat” hypothesis of Werner (1749-1817). Werner conceived the terrestrial globe as encircled with successive mineral envelopes, basing his scheme of universal stratification upon that order of sequence among rocks, which he had observed within the narrow confines of his native district in Germany. His hypothesis, after leading many scientists astray, was ultimately discredited and laughed out of existence. For it finally became evident to all observers that Werner’s scheme did not fit the facts, and men were able to witness with their own eyes the simultaneous deposition, in separate localities, of sediments which differed radically in their mineral contents and texture. Thus it came to pass that this classification of strata according to their mineral nature and physical appearance lost all value as an absolute time-scale, while the theory itself was relegated to the status of a curious and amusing episode in the history of scientific fiascos.

Thanks, however, to Wm. Smith and to Cuvier, the discarded onion-coat hypothesis did not perish utterly, but was rehabilitated and bequeathed to us in a new and more subtle form. Werner’s fundamental idea of the universality of a given kind of deposit was retained, but his mineral strata were replaced by fossiliferous strata, the lithological onion-coats of Werner being superseded by the biological onion-coats of our modern theory. The geologist of today discounts physical appearance, and classifies strata according to their fossil, rather than their mineral, contents, but he stands committed to the same old postulate of universal deposits. He has no hesitation in synchronizing such widely-scattered formations as the Devonian deposits of New York State, England, Germany, and South America. He pieces them all together as parts of a single system of rocks. He has no misgiving as to the universal applicability of the European scheme of stratigraphic classification, but assures us, in the words of the geologist, Wm. B. Scott, that: “Even the minuter divisions, the subdivisions and zones of the European Jura, are applicable to the classification of the South American beds.” (“Introduction to Geology,” p. 681f.) The limestone and sandstone strata of Werner are now things of the past, but, in their stead, we have, to quote the criticism of Herbert Spencer, “groups of formations which everywhere succeed each other in a given order, and are severally everywhere of the same age. Though it may not be asserted that these successive systems are universal, yet it seems to be tacitly assumed that they are so.... Though probably no competent geologist would contend that the European classification of strata is applicable to the globe as a whole, yet most, if not all geologists, write as though it were so.... Must we not say that though the onion-coat hypothesis is dead, its spirit is traceable, under a transcendental form, even in the conclusions of its antagonists.” (“Illustrations of Universal Progress,” pp. 329-380, ed. of 1890.)

But overlooking, for the moment, the mechanical absurdity involved in the notion of a regular succession of universal layers of sediment, and conceding, for the sake of argument, that the substitution of fossiliferous, for lithological, strata may conceivably have remedied the defects of Werner’s geological time-scale, let us confine ourselves to the one question, which, after all, is of prime importance, whether, namely, without the aid of Procrustean tactics, the actual facts of geology can be brought into alignment with the doctrine of an invariable order of succession among fossil types, and its sequel, the intrinsic time-value of index fossils. The question, in other words, is whether or not a reliable time-scale can be based on the facts of fossiliferous stratification as they are observed to exist in the concrete. Price’s answer is negative, and he formulates several empirical laws to express the concrete facts, on which he bases his contention. The laws and facts to which he appeals may be summarized as follows:

1. The concrete facts of geology do not warrant our singling out any fossiliferous deposit as unquestionably the oldest, and hence we have no reliable starting-point for our time-scale, because:

(a) We may lay it down as an empirical law that “any kind of fossiliferous rock (even the ‘youngest’), that is, strata belonging to any of the systems or other subdivisions, may rest directly upon the Archæan or primitive crystalline rocks, without any other so-called ‘younger’ strata intervening; also these rocks, Permian, Cretaceous, Tertiary, or whatever thus reposing directly on the Archæan may be themselves crystalline or wholly metamorphic in texture. And this applies not alone to small points of contact, but to large areas.”

(b) Conversely: any kind of fossiliferous strata (even the “oldest”) may not only constitute the surface rocks over wide areas,[8] but may consist of loose, unconsolidated materials, thus in both position and texture resembling the “late” Tertiaries or the Pleistocene—“In some regions, notably in the Baltic province and in parts of the United States,” says John Allen Howe, alluding to the Cambrian rocks around the Baltic Sea and in Wisconsin, “the rocks still retain their original horizontality of deposition, the muds are scarcely indurated, and the sands are incoherent.” (Encycl. Brit., vol. V, p. 86.)

A large number of striking instances are cited by Price to substantiate the foregoing rule and its converse. The impression left is that not only is the starting-point of the time-scale in doubt, but that, if we were to judge the age of the rocks by their physical appearance and position, we could not accept the conventional verdicts of modern geology, which makes fossil evidence prevail over every other consideration.

2. When two contiguous strata are parallel to each other, and there is no indication of disturbance in the lower bed, nor any evidence of erosion along the plane of contact, the two beds are said to exhibit conformity, and this is ordinarily interpreted by geologists as a sign that the upper bed has been laid down in immediate sequence to the lower, and that there has been a substantial continuity of deposition, with no long interval during which the lower bed was exposed as surface to the agents of erosion. When such a conformity exists, as it frequently does, between a “recent” stratum, above, and what is said (according to the testimony of the fossils) to be a very “ancient” stratum, below, and though the two are so alike lithologically as to be mistaken for one and the same formation, nevertheless, such a conformity is termed a “non-evident disconformity,” or “deceptive conformity,” implying that, inasmuch as the “lost interval,” representing, perhaps, a lapse of “several million years,” is entirely unrecorded by any intervening deposition, or any erosion, or any disturbance of the lower bed, we should not have suspected that so great a hiatus had intervened, were it not for the testimony of the fossils. Price cites innumerable examples, and sums them up in the general terms of the following empirical law: “Any sort of fossiliferous formation may occur on top of any other ‘older’ fossiliferous formation, with all the physical evidences of perfect conformity, just as if these alleged incongruous or mismated formations had in reality followed one another in quick succession.”

A quotation from Schuchert’s “Textbook of Geology,” (1920), may be given by way of illustration: “The imperfection,” we read, “of the geologic column is greatest in the interior of North America and more so in the north than in the south. This imperfection is in many places very marked, since an entire period or several periods may be absent. With such great breaks in the local sections the natural assumption is that these gaps are easily seen in the sequence of the strata, but in many places the beds lie in such perfect conformity upon one another that the breaks are not noticeable by the eye and can be proved to exist only by the entombed fossils on each side of a given bedding plane.... Stratigraphers are, as a rule, now fully aware of the imperfections in the geologic record, but the rocks of two unrelated formations may rest upon each other with such absolute conformability as to be completely deceptive. For instance, in the Bear Grass quarries at Louisville, Ky., a face of limestone is exposed in which the absolute conformability of the beds can be traced for nearly a mile, and yet within 5 feet of vertical thickness is found a Middle Silurian coral bed overlain by another coral zone of Middle Devonian. The parting between these two zones is like that between any two limestone beds, but this insignificant line represents a stratigraphic hiatus the equivalent of the last third of Silurian and the first of Devonian time. But such disconformities are by no means rare, in fact are very common throughout the wide central basin area of North America.” (Op. cit., II, pp. 586-588.)

In such cases, the stratigraphical relations give no hint of any enormous gap at the line of contact. On the contrary, there is every evidence of unbroken sequence, and the physical appearances are as if these supposed “geological epochs” had never occurred in the localities, of which there is question. Everything points to the conclusion that the alleged long intervals of time between such perfectly conformable, and, often, lithologically identical, formations are a pure fiction elaborated for the purpose of bolstering up the dogma of the universal applicability of the European classification of fossiliferous rocks. Why not take the facts as we find them? Why resort to tortuous explanations for the mere purpose of saving an arbitrary time-scale? Why insist on a definite time-value for fossils, when it drives us to the extremity of discrediting the objective evidence of physical facts in deference to the preconceptions of orthodox geology? Were it not for theoretical considerations, these stratigraphic facts would be taken at their face value, and the need of saving the reputation of the fossil as an infallible time index is not sufficiently imperative to warrant so drastic a revision of the physical evidence.

3. The third class of facts militating against the time-value of index fossils, are what Price describes as “deceptive conformities turned upside down,” and what orthodox geology tries to explain away as “thrusts,” “thrust faults,” “overthrusts,” “low-angle faulting,” etc.[9] In instances of this kind we find the accepted order of the fossiliferous strata reversed in such a way that the “younger” strata are conformably overlain by “older” strata, and the “older” strata are sometimes interbedded between “younger” strata. “In many places all over the world,” says Price, “fossils have been found in a relative order which was formerly thought to be utterly impossible. That is, the fossils have been found in the ‘wrong’ order, and on such a scale that there can be no mistake about it. For when an area 500 miles long and from 20 to 50 miles wide is found with Palæozoic rocks on top, or composing the mountains, and with Cretaceous beds underneath, or composing the valleys, and running under these mountains all around, as in the case of the Glacier National Park and the southern part of Alberta, the old notion about the exact and invariable order of the fossils has to be given up entirely.”

Price formulates his third law as follows: “Any fossiliferous formation, ‘old’ or ‘young,’ may occur conformably on any other fossiliferous formation, ‘younger’ or ‘older.’” The corollary of this empirical law is that we are no longer justified in regarding any fossils as intrinsically older than other fossils, and that our present classification of fossiliferous strata has a taxonomic, rather than a historical, value.

Low-angle faulting is the phenomenon devised by geologists to meet the difficulty of “inverted sequence,” when all other explanations fail. Immense mountain masses are said to have been detached from their roots and pushed horizontally over the surface (without disturbing it in the least), until they came finally to rest in perfect conformity upon “younger” strata, so that the plane of slippage ended by being indistinguishable from an ordinary horizontal bedding plane. These gigantic “overthrusts” or “thrust faults” are a rather unique phenomenon. Normal faulting is always at a high angle closely approaching the vertical, but “thrust faults” are at a low angle closely approximating the horizontal, and there is enormous displacement along the plane of slippage. The huge mountain masses are said to have been first lifted up and then thrust horizontally for vast distances, sometimes for hundreds of miles, over the face of the land, being thus pushed over on top of “younger” rocks, so as to repose upon the latter in a relation of perfectly conformable superposition. R. G. McConnell, of the Canadian Survey, comments on the remarkable similarity between these alleged “thrust planes” and ordinary stratification planes, and he is at a loss to know why the surface soil was not disturbed by the huge rock masses which slid over it for such great distances. Speaking of the Bow River Gap, he says: “The fault plane here is nearly horizontal, and the two formations, viewed from the valley appear to succeed one another conformably,” and then having noted that the underlying Cretaceous shales are “very soft,” he adds that they “have suffered little by the sliding of the limestones over them.” (An. Rpt. 1886, part D., pp. 33, 34, 84.) Credat Iudaeus Apella, non ego!

Schuchert describes the Alpine overthrust as follows: “The movement was both vertical and thrusting from the south and southeast, from the southern portion of Tethys, elevating and folding the Tertiary and older strata of the northern areas of this mediterranean into overturned, recumbent, and nearly horizontal folds, and pushing the southern or Lepontine Alps about 60 miles to the northward into the Helvetic region. Erosion has since carved up these overthrust sheets, leaving remnants lying on foundations which belong to a more northern portion of the ancient sea. Most noted of these residuals of overthrust masses is the Matterhorn, a mighty mountain without roots, a stranger in a foreign geologic environment,” (Pirsson & Schuchert’s “Textbook of Geology,” 1920, II, p. 924.)

With such a convenient device as the “overthrust” at his disposal, it is hard to see how any possible concrete sequence of fossiliferous strata could contradict the preconceptions of an evolutionary geologist. The hypotheses and assumptions involved, however, are so tortuous and incredible, that nothing short of fanatical devotion to the theory of transformism can render them acceptable. “Examples,” says Price, “of strata in the ‘wrong’ order were first reported from the Alps nearly half a century ago. Since that time, whole armfuls of learned treatises in German, in French, and in English have been written to explain the wonderful conditions there found. The diagrams that have been drawn to account for the strange order of the strata are worthy to rank with the similar ones by the Ptolemaic astronomers picturing the cycles and epicycles required to explain the peculiar behavior of the heavenly bodies in accordance with the geocentric theory of the universe then prevailing.... In Scandinavia, a district some 1,120 miles long by 80 miles wide is alleged to have been pushed horizontally eastward ‘at least 86 miles.’ (Schuchert.) In Northern China, one of these upside down areas is reported by the Carnegie Research Expedition to be 500 miles long.” (“The New Geology,” 1923, pp. 633, 634.)

Nor are the epicyclic subterfuges of the evolutionary geologist confined to “deceptive conformities” and “overthrusts.” His inventive genius has hit upon other methods of explaining away inconvenient facts. When, for example, “younger” fossils are found interbedded with “older” fossils, and the discrepancy in time is not too great, he rids himself of the difficulty of their premature appearance by calling them a “pioneer colony.” Similarly, when a group of “characteristic” fossils occur in one age, skip another “age,” and recur in a third, he recognizes the possibility of “recurrent faunas,” some of these faunas having as many as five successive “recurrences.” Clearly, the assumption of gradual approximation and the dogma that the lower preceded the higher forms of life are things to be saved at all costs, and it is a foregone conclusion that no facts will be suffered to conflict with these irrevisable articles of evolutionary faith. “What is the use,” exclaims Price, “of pretending that we are investigating a problem of natural science, if we already know beforehand that the lower and more generalized forms of animals and plants came into existence first, and the higher and the more specialized came only long afterwards, and that specimens of all these successive types have been pigeonholed in the rocks in order to help us illustrate this wonderful truth?” (Op. cit., pp. 667, 668.)

The predominance of extinct species in certain formations is said to be an independent argument of their great age. Most of the species of organisms found as fossils in Cambrian, Ordovician, and Silurian rocks are extinct, whereas modern types abound in Cretaceous and Tertiary rocks. Hence it is claimed that the former must be vastly older than the latter. But this argument gratuitously assumes the substantial perfection of the stone record of ancient life and unwarrantedly excludes the possibility of a sudden impoverishment of the world’s flora and fauna as the result of a sweeping catastrophe, of which our present species are the fortunate survivors. Now the fact that certain floras and faunas skip entire systems of rocks to reappear only in later formations is proof positive that the record of ancient life is far from being complete, and we have in the abundant fossil remains of tropical plants and animals, found in what are now the frozen arctic regions, unmistakable evidence of a sudden catastrophic change by which a once genial climate “was abruptly terminated. For carcasses of the Siberian elephants were frozen so suddenly and so completely that the flesh has remained untainted.” (Dana.) Again, the mere fact of extinction tells us nothing about the time of the extinction. For this we are obliged to fall back on the index fossil whose inherent time-value is based on the theory of evolution and not on stratigraphy. Hence the argument from extinct species is not an independent argument.

To sum up, therefore, the aprioristic evolutional series of fossils is not a genuine time-scale. The only safe criterion of comparative age is that of stratigraphic superposition, and this is inapplicable outside of limited local areas.[10] The index fossil is a reliable basis for the chronological correlation of beds only in case one is already convinced on other grounds of the actuality of evolution, but for the unbiased inquirer it is destitute of any inherent time-value. In other words, we can no longer be sure that a given formation is old merely because it happens to contain Cambrian fossils, nor that a rock is young merely because it chances to contain Tertiary fossils. Our present classification of rocks according to their fossil contents is purely arbitrary and artificial, being tantamount to nothing more than a mere taxonomical classification of the forms of ancient life on our globe, irrespective of their comparative antiquity. This scheme of classification is, indeed, universally applicable, and places can usually be found in it for new fossiliferous strata, whenever and wherever discovered. Its universal applicability, however, is due not to any prevalent order of invariable sequence among fossiliferous strata, but solely to the fact that the laws of biological taxonomy and ecology are universal laws which transcend spatial and temporal limitation. If a scheme of taxonomy is truly scientific, all forms of life, whether extant or extinct, will fit into it quite readily.

The anomalies of spatial distribution constitute a sixth difficulty for transformistic palæontology. In constructing a phylogeny the most diverse and widely-separated regions are put under tribute to furnish the requisite fossils, no heed being paid to what are now at any rate impassable geographical barriers, not to speak of the climatic and environmental limitations which restrict the migrations of non-cosmopolitan species within the boundaries of narrow habitats. Hypothetical lineages of a modern form of life are frequently constructed from fossil remains found in two or more continents separated from one another by immense distances and vast oceanic expanses. When taxed with failure to plausibleize this procedure, the evolutionist meets the difficulty by hypothecating wholesale and devious migrations to and fro, and by raising up alleged land bridges to accommodate plants and animals in their suppositional migrations from one continent to another, etc.

The European horse, with his so-called ancestry interred, partly in the Tertiary deposits of Europe, but mostly in those of North America, is a typical instance of these anomalies in geographical distribution. It would, of course, be preposterous to suppose that two independent lines of descent could have fortuitously terminated in the production of one and the same type, namely, the genus Equus. Moreover, to admit for a moment that the extinct American Equus and the extant European Equus had converged by similar stages from distinct origins would be equivalent, as we have seen, to a surrender of the basic postulate that structural similarity rests on the principle of inheritance. Nothing remains, therefore, but to hypothecate a Tertiary land bridge between Europe and North America.

Modern geologists, however, are beginning to resent these arbitrary interferences with their science in the interest of biological theories. Land bridges, they rightly insist, should be demonstrated by means of positive geological evidence and not by the mere exigencies of a hypothetical genealogy. Whosoever postulates a land bridge between continents should be able to adduce solid reasons, and to assign a mechanism capable of accomplishing the five-mile uplift necessary to bring a deep-sea bottom to the surface of the hydrosphere. Such an idea is extravagant and not to be easily entertained in our day, when geologists are beginning to understand the principle of isostasy. To-day, the crust of the earth, that is, the entire surface of the lithosphere, is conceived as being constituted of earth columns, all of which rest with equal weight upon the level of complete compensation, which exists at a depth of some 76 miles below land surfaces. At this depth viscous flows and undertows of the earth take place, compensating all differences of gravitational stress. Hence the materials constituting a mountain column are thought to be less dense than those constituting the surrounding lowland columns, and for this reason the mountains are buoyed up above the surrounding landscape. The columns under ocean bottoms, on the contrary, are thought to consist of heavy materials like basalt, which tend to depress the column. To raise a sea floor, therefore, some means of producing a dilatation of these materials would have to be available. Arthur B. Coleman called attention to this difficulty in his Presidential Address to the Geological Society of America (December 29, 1915), and we cannot do better than quote his own statement of the matter here:

“Admitting,” he says, “that in the beginning the lithosphere bulged up in places, so as to form continents, and sagged in other places, so as to form ocean beds, there are interesting problems presented as to the permanence of land and seas. All will admit marginal changes affecting large areas, but these encroachments of the sea on the continents and the later retreats may be of quite a subordinate kind, not implying an interchange of deep-sea bottoms and land surfaces. The essential permanence of continents and oceans has been firmly held by many geologists, notably Dana among the older ones, and seems reasonable; but there are geologists, especially palæontologists, who display great recklessness in rearranging land and sea. The trend of a mountain range, or the convenience of a running bird, or a marsupial afraid to wet his feet seems sufficient warrant for hoisting up any sea bottom to connect continent with continent. A Gondwana Land arises in place of an Indian Ocean and sweeps across to South America, so that a spore-bearing plant can follow up an ice age; or an Atlantis ties New England to Old England to help out the migrations of a shallow-water fauna; or a ‘Lost Land of Agulhas’ joins South Africa and India.

“It is curious to find these revolutionary suggestions made at a time when geodesists are demonstrating that the earth’s crust over large areas, and perhaps everywhere, approaches a state of isostatic equilibrium, and that isostatic compensation is probably complete at a depth of only 76 miles” ... and (having noted the difference of density that must exist between the continental, and submarine, earth columns) Coleman would have us bear in mind “that to transform great areas of sea bottom into land it would be necessary either to expand the rock beneath by several per cent or to replace heavy rock, such as basalt, by lighter materials, such as granite. There is no obvious way in which the rock beneath a sea bottom can be expanded enough to lift it 20,000 feet, as would be necessary in parts of the Indian Ocean, to form a Gondwana land; so one must assume that light rocks replace heavy ones beneath a million square miles of ocean floor. Even with unlimited time, it is hard to imagine a mechanism that could do the work, and no convincing geological evidence can be brought forward to show that such a thing ever took place.... The distribution of plants and animals should be arranged for by other means than by the wholesale elevation of ocean beds to make dry land bridges for them.” (Smithson. Inst. Rpt. for 1916, pp. 269-271.)

A seventh anomaly of palæontological phylogeny is what may be described as contrariety of direction. We are asked to believe, for example, that in mammals racial development resulted in dimensional increase. The primitive ancestor of mammoths, mastodons, and elephants is alleged to have been the Moeritherium, “a small tapirlike form, from the Middle Eocene Qasr-el-Sagha beds of the Fayûm in Egypt.... Moeritherium measured about 3½ feet in height.” (Lull: Smithson. Inst. Rpt. for 1908, pp. 655, 656.) The ancestor of the modern horse, we are told, was “a little animal less than a foot in height, known as Eohippus, from the rocks of the Eocene age.” (Woodruff: “Foundations of Biology,” p. 361.) In the case of insects, on the other hand, we are asked to believe the exact reverse, namely, that racial development brought about dimensional reduction. “In the middle of the Upper Carboniferous periods,” says Anton Handlirsch, “the forest swamps were populated with cockroaches about as long as a finger, dragonfly-like creatures with a wing spread of about 2½ feet, while insects that resemble our May flies were as big as a hand.” (“Die fossilen Insekten, und die Phylogenie der recenten Formen,” 1908, L. c., p. 1150.) Contrasting one of these giant palæozoic dragonflies, Meganeura monyi Brongn., with the largest of modern dragonflies, Aeschna grandis L., Chetverikov exclaims with reference to the latter: “What a pitiful pigmy it is and its specific name (grandis) sounds like such a mockery.” (Smithson. Inst. Rpt. for 1918, p. 446.) Chetverikov, it is true, proposes a teleological reason for this progressive diminution, but the fact remains that for dysteleological evolutionism, which dispenses with the postulate of a Providential coördination and regulation of natural agencies, this diminuendo of the “evolving” insects stands in irreconcilable opposition to the crescendo of the “evolving” mammals, and constitutes a difficulty which a purely mechanistic philosophy can never surmount.

Not to prolong excessively this already protracted enumeration of discrepancies between fossil fact and evolutionary assumption, we shall mention, as an eighth and final difficulty, the indubitable persistence of unchanged organic types from the earliest geological epochs down to the present time. This phenomenon is all the more wonderful in view of the fact that the decision as to which are to be the “older” and which the “younger” strata rests with the evolutionary geologist, who is naturally disinclined to admit the antiquity of strata containing modern types, and whose position as arbiter enables him to date formations aprioristically, according to the exigencies of the transformistic theory. Using, as he does, the absence of modern types as an express criterion of age, and having, as it were, his pick among the various fossiliferous deposits, one would expect him to be eminently successful in eliminating from the stratigraphic groups selected for senior honors all strata containing fossil types identical with modern forms. Since, however, even the most ingenious sort of geological gerrymandering fails to make this elimination complete, we must conclude that the evidence for persistence of type is inescapable and valid under any assumption.

When we speak of persistent types, we mean generic and specific, rather than phyletic, types, although it is assuredly true that the persistence of the great phyla, from their abrupt and contemporaneous appearance in Cambrian and pre-Cambrian rocks down to the present day, constitutes a grave difficulty for progressive evolution in general and monophyletic evolution in particular. All the great invertebrate types, such as the protozoa, the annelida, the brachiopoda, and large crustaceans called eurypterids, are found in rocks of the Proterozoic group, despite the damaged condition of the Archæan record, while in the Cambrian they are represented by a great profusion of forms. “The Lower Cambrian species,” says Dana, “have not the simplicity of structure that would naturally be looked for in the earliest Palæozoic life. They are perfect of their kind and highly specialized structures. No steps from simple kinds leading up to them have been discovered; no line from the protozoans up to corals, echinoderms, or worms, or from either of these groups up to brachiopods, mollusks, trilobites, or other crustaceans. This appearance of abruptness in the introduction of Cambrian life is one of the striking facts made known by geology.” (“Manual,” p. 487.) Thus, as we go backward in time, we find the great organic phyla retaining their identity and showing no tendency to converge towards a common origin in one or a few ancestral types. For this reason, as we shall see presently, geologists are beginning to relegate the evolutionary process to unknown depths below the explored portion of the “geological column.” What may lurk in these unfathomed profundities, it is, of course, impossible to say, but, if we are to judge by that part of the column which is actually exposed to view, there is no indication whatever of a steady progression from lower, to higher, degrees of organization, and it takes all the imperturbable idealism of a scientific doctrinaire to discern in such random, abrupt, and unrelated “origins” any evidence of what Blackwelder styles “a slow but steady increase in complexity of structure and in function.” (Science, Jan. 27, 1922, p. 90.)

But, while the permanence of phyletic types excludes progress, that of generic and specific types excludes change, and hence it is in the latter phenomenon, especially, that the theory of transformism encounters a formidable difficulty. Palæobotany furnishes numerous examples of the persistence of unchanged plant forms. Ferns identical with the modern genus Marattia occur in rocks of the Palæozoic group. Cycads indistinguishable from the extant genera Zamia and Cycas are found in strata belonging to the Triassic system, etc., etc.

The same is true of animal types. In all the phyla some genera and even species have persisted unchanged from the oldest strata down to the present day. Among the Protozoa, for example, we have the genus Globigerina (one of the Foraminifera), some modern species of which are identical with those found in the Cretaceous. To quote the words of the Protozoologist, Charles A. Kofoid: “The Protozoa are found in the oldest fossiliferous rocks and the genera of Radiolaria therein conform rather closely to genera living today, while the fossil Dinoflagellata of the flints of Delitzsch are scarcely distinguishable from species living in the modern seas. The striking similarities of the most ancient fossil Protozoa to recent ones afford some ground for the inference that the Protozoa living today differ but little from those when life was young.” (Science, April 6, 1923, p. 397.)

The Metazoa offer similar examples of persistence. Among the Cœlenterata, we have the genus Springopora, whose representatives from the Carboniferous limestones closely resemble some of the present-day reef builders of the East Indies. Species of the brachiopod genera Lingula and Crania occurring in the Cambrian rocks are indistinguishable from species living today, while two other modern genera of the Brachiopoda, namely, Rhynchonella and Discina, are represented among the fossils found in Mesozoic formations. Terebratulina striata, a fossil species of brachiopod occurring in the rocks belonging to the Cretaceous system, is identical with our modern species Terebratulina caput serpentis. Among the Mollusca such genera as Arca, Nucula, Lucina, Astarte, and Nautilus have had a continuous existence since the Silurian, while the genera Lima and Pecten can be traced to the Permian. One genus Pleurotomaria goes back to pre-Cambrian times. As to Tertiary fossils, Woods informs us that “in some of the later Cainozoic formations as many as 90 per cent of the species of mollusks are still living.” (“Palæontology,” 1st ed., p. 2.) Among the Echinodermata, two genera, Cidaris (a sea urchin) and Pentacrinus (a crinoid) may be mentioned as being persistent since the Triassic (“oldest” system of the Mesozoic group). Among the Arthropoda, the horseshoe crab Limulus polyphemus has had a continuous existence since the Lias (i.e. the lowest series of the Jurassic system). Even among the Vertebrata we have instances of persistence. The extant Australian genus Ceratodus, a Dipnoan, has been in existence since the Triassic. Among the fossils of the Jurassic (middle system of the Mesozoic group), Sharks, Rays, and Chimaeroids occur in practically modern forms, while some of the so-called “ganoids” are extremely similar to our present sturgeons and gar pikes—“Some of the Jurassic fishes approximate the teleosts so closely that it seems arbitrary to call them ganoids.” (Scott.)

The instances of persistence enumerated above are those acknowledged by evolutionary palæontologists themselves. This list could be extended somewhat by the addition of several other examples, but even so, it would still be small and insufficient to tip the scales decisively in favor of fixism. On the other hand, we must not forget that the paucity of this list is due in large measure to the fact that our present method of classifying fossiliferous strata was deliberately framed with a view to excluding formations containing modern types from the category of “ancient” beds. Moreover, orthodox palæontology has minimized the facts of persistence to an extent unwarranted even by its own premises. As the following considerations indicate, the actual number of persistent types is far greater, even according to the evolutionary time-scale, than the figure commonly assigned.

First of all, we must take into account the deplorable, if not absolutely dishonest, practice, which is in vogue, of inventing new names for the fossil duplicates of modern species, in order to mask or obscure an identity which conflicts with evolutionary preconceptions. When a given formation fails to fit into the accepted scheme by reason of its fossil anachronisms, or when, to quote the words of Price, “species are found in kinds of rock where they are not at all expected, and where, according to the prevailing theories, it is quite incredible that they should be found ... the not very honorable expedient is resorted to of inventing a new name, specific or even generic, to disguise and gloss over the strange similarity between them and the others which have already been assigned to wholly different formations.” (“The New Geology,” p. 291.) The same observation is made by Heilprin. “It is practically certain,” says the latter, “that numerous forms of life, exhibiting no distinctive characters of their own, are constituted into distinct species for no other reason than that they occur in formations widely separated from those holding their nearest kin.” (“Geographical and Geological Distribution of Animals,” pp. 183, 184.) An instance of this practice occurs in the foregoing list, where a fossil brachiopod identical with a modern species receives the new specific name “striata.” Its influence is also manifest in the previously quoted apology of Scott for calling teleost-like fish “ganoids.”

We must also take into account the imperfection of the fossil record, which is proved by the fact that most of the acknowledged “persistent types” listed above “skip” whole systems and even groups of “later” rocks (which are said to represent enormous intervals of time), only to reappear, at last, in modern times. It is evident that their existence has been continuous, and yet they are not represented in the intervening strata. Clearly, then, the fossil record is imperfect, and we must conclude that many of our modern types actually did exist in the remote past, without, however, leaving behind any vestige of their former presence.

Again, we must frankly confess our profound ignorance with respect to the total number and kinds of species living in our modern seas. Hence our conventional distinction between “extinct” and “extant” species has only a provisory value. Future discoveries will unquestionably force us to admit that many of the species now classed as “extinct” are in reality living forms, which must be added to our list of “persistent types.” “It is by no means improbable,” says Heilprin, “that many of the older genera, now recognized as distinct by reason of our imperfect knowledge concerning their true relationships, have in reality representatives in the modern sea.” (Op. cit. pp. 203, 204.)

Finally, the whole of our present taxonomy of plants and animals, both living and fossil, stands badly in need of revision. Systematists, as we have seen in the second chapter, base their classifications mainly on what they regard as basic or homologous structures, in contradistinction to superficial or adaptive characters. Both kinds of structure, however, are purely somatic, and somatic characters, as previously observed, are not, by themselves, a safe criterion for discriminating between varieties and species. In the light of recent genetical research, we cannot avoid recognizing that there has been far too much “splitting” of organic groups on the basis of differences that are purely fluctuational, or, at most, mutational. Moreover, the distinction between homologous and adaptive structures is often arbitrary and largely a matter of personal opinion, especially when numerous specimens are not available. What the “Cambridge Natural History” says in allusion to the Asteroidea is of general application. “While there is considerable agreement,” we read, “amongst authorities as to the number of families, or minor divisions of unequivocal relationship, to be found in the class Asteroidea, there has been great uncertainty both as to the number and limits of the orders into which the class should be divided, and also as to the limits of the various species. The difficulty about the species is by no means confined to the group Echinodermata; in all cases where the attempt is made to determine species by an examination of a few specimens of unknown age there is bound to be uncertainty; the more so, as it becomes increasingly evident that there is no sharp line to be drawn between local varieties and species. In Echinodermata, however, there is the additional difficulty that the acquisition of ripe genital cells does not necessarily mark the termination of growth; the animals can continue to grow and at the same time slightly alter their characters. For this reason many of the species described may be merely immature forms....

“The disputes, however, as to the number of orders included in the Asteroidea proceed from a different cause. The attempt to construct detailed phylogenies involves the assumption that one set of structures, which we take as the mark of the class, has remained constant, whilst the others which are regarded as adaptive, may have developed twice or thrice. As the two sets of structures are about of equal importance it will be seen to what an enormous extent the personal equation enters in the determination of these questions.” (Op. cit., vol. I, pp. 459, 460.)

In dealing with fossil forms, these difficulties of the taxonomist are intensified: (1) by the sparse, badly-preserved, and fragmentary character of fossil remains; (2) by the fact that here breeding experiments are impossible, and hence the diagnosis based on external characters cannot be supplemented by a diagnosis of the germinal factors. Fossil taxonomy is, in consequence, extremely arbitrary and unreliable. Many fossil forms classed as distinct species, or even as distinct genera, may be nothing more than fluctuants, mutants, hybrids, or immature stages of well-known species living today. Again, many fossils mistaken for distinct species are but different stages in the life-history of a single species, a mistake, which is unavoidable, when specimens are few and the age of the specimens unknown. The great confusion engendered in the classification of the hydrozoa by nineteenth-century ignorance of the alternation of hydroid and medusoid generations is a standing example of the danger of classifying forms without a complete knowledge of the entire life-cycle. When due allowance is made for mutation, hybridization, metagenesis, polymorphism, age and metamorphosis, the number of distinct fossil species will undergo considerable shrinkage. Nor must we overlook the possibility of environmentally-induced modifications. Many organisms, such as mollusks, undergo profound alteration as a result of some important, and, perhaps, relatively permanent, change in their environmental conditions, though such alterations affect only the phenotype, and do not involve a corresponding change in the specific genotype, i.e. the germinal constitution of the race.

In the degree that these considerations are taken into account the number of “extinct” fossil species will diminish and the number of “persistent” species will increase. This is a consummation devoutly to be wished for, but it means that hundreds of thousands of described species must needs be reviewed for the purpose of weeding out the duplicates, and who will have the knowledge, the courage, or even the span of life, necessary to accomplish so gigantic a task?

But so far as the practical purposes of our argument are concerned, the accepted list of persistent types needs no amplification. It suffices, as it stands, to establish the central fact (which, for the rest, is admitted by everyone) that some generic and even specific types have remained unchanged throughout the enormous lapse of time which has intervened between the deposition of the oldest strata and the advent of the present age. Our current theories, far from diminishing the significance of this fact, tend to intensify it by computing the duration of such persistence in millions, rather than in thousands, of years. Now, whatever one’s views may be on the subject of transformism, this prolonged permanence of certain genera and species is an indubitable fact, which is utterly irreconcilable with a universal law of organic evolution. The theory of transformism is impotent to explain an exception so palpable as this; for persistence and transmutation cannot be subsumed under one and the same principle. That which accounts for change cannot account for unchange. Yet unchange is an observed fact, while the change, in this case, is an inferred hypothesis. Hence, even if we accept the principle of transformism, there will always be scope for the principle of permanence. The extraordinary tenacity of type manifested by persistent genera and species is a phenomenon deserving of far more careful study and investigation than the evolutionally-minded scientist of today deigns to bestow upon it. To the latter it may seem of little consequence, but, to the genuine scientist, the actual persistence of types should be of no less interest than their possible variability.

With these reflections, our criticism of the palæontological argument terminates. The enumeration of its various deficiencies was not intended as a refutation. To disprove the theory of organic evolution is a feat beyond our power to accomplish. We can only adduce negative evidence, whose scope is to show that the various evolutionary arguments are inconsequential or inconclusive. We cannot rob the theory of its intrinsic possibility, and sheer justice compels us to confess that certain facts, like those of symbiotic preadaptation, lend themselves more readily to a transformistic, than to a fixistic, interpretation. On the other hand, nothing is gained by ignoring flaws so obvious and glaring as those which mar the cogency of palæontological “evidence.” The man who would gloss them over is no true friend either of Science or of the scientific theory of Evolution! They represent so many real problems to be frankly faced and fully solved, before the palæontological argument can become a genuine demonstration. But until such time as a demonstration of this sort is forthcoming, the evolutionist must not presume to cram his unsubstantiated theory down our reasonably reluctant throats. To accept as certain what remains unproved, is to compromise our intellectual sincerity. True certainty, which rests on the recognition of objective necessity, will never be attainable so long as difficulties that sap the very base of evolutionary argumentation are left unanswered; and, as for those who, in the teeth of discordant factual evidence, profess, nevertheless, to have certainty regarding the “fact” of evolution, we can only say that such persons cannot have a very high or exacting conception of what scientific certainty really means.

For the rest, it cannot even be said that the palæontological record furnishes good circumstantial evidence that our globe has been the scene of a process of organic evolution. In fact, so utterly at variance with this view is the total impression conveyed by the visible portion of the geological column, that the modern geologist proposes, as we have seen, to probe depths beneath its lowest strata for traces of that alleged transmutation, which higher horizons do not reveal. There are six to eight thick terranes below the Cambrian, we are told, and igneous masses that were formerly supposed to be basal have turned out to be intrusions into sedimentary accumulations, all of which, of course, is fortunate for the theory of organic evolution, as furnishing it with a sadly needed new court of appeal. The bottom, so to speak, has dropped out of the geological column, and Prof. T. C. Chamberlin announces the fact as follows: “The sharp division into two parts, a lifeless igneous base and a sedimentary fossiliferous superstructure, has given place to the general concept of continuity with merely minor oscillations in times and regions of major activity. Life has been traced much below the Cambrian, but its record is very imperfect. The recent discoveries of more ample and varied life in the lower Palæozoic, particularly the Cambrian, implies, under current evolutional philosophy, a very great downward extension of life. In the judgment of some biologists and geologists, this extension probably reaches below all the pre-Cambrian terranes as yet recognized, though this pre-Cambrian extension is great. The ‘Azoic’ bottom has retired to depths unknown. This profoundly changes the life aspect of the ‘column.’” (Science, Feb. 8, 1924, p. 128.) All this is doubtless true, but such an appeal, from the known to the unknown, from the actual to the possible, is not far-removed from a confession of scientific insolvency. Life must, of course, have had an earlier history than that recorded in the pre-Cambrian rocks. But even supposing that some portion of an earlier record should become accessible to us, it could not be expected to throw much light on the problem of organic origins. Most of the primordial sediments have long since been sapped and engulfed by fiery magmas, while terranes less deep have, in all probability, been so metamorphosed that every trace of their fossil contents has perished. The sub-Archæan beginnings of life will thus remain shrouded forever in a mystery, which we have no prospect of penetrating. Hence it is the exposed portion of the geological column which continues and will continue to be our sole source of information, and it is preëminently on this basis that the evolutionary issue will have to be decided.

Yet what could be more enigmatic than the rock record as it stands? For in nature it possesses none of that idealized integrity and coherence, with which geology has invested it for the purpose of making it understandable. Rather it is a mighty chaos of scattered and fragmentary fossiliferous formations, whose baffling complexity, discontinuity, and ambiguity tax the ingenuity of the most sagacious interpreters. Transformism is the key to one possible synthesis, which might serve to unify that intricate mass of facts, but it is idle to pretend that this theory is the unique and necessary corollary of the facts as we find them. The palæontological argument is simply a theoretical construction which presupposes evolution instead of proving it. Its classic pedigrees of the horse, the camel, and the elephant are only credible when we have assumed the “fact” of evolution, and even then, solely upon condition that they claim to approximate, rather than assign, the actual ancestry of the animals in question. In palæontology, as in the field of zoölogy, evolution is not a conclusion, but an interpretation. In palæontology, otherwise than in the field of genetics, evolution is not amenable to the check of experimental tests, because here it deals not with that which is, but with that which was. Here the sole objective basis is the mutilated and partially obliterated record of a march of events, which no one has observed and which will never be repeated. These obscure and fragmentary vestiges of a vanished past, by reason of their very incompleteness, lend themselves quite readily to all sorts of theories and all sorts of speculations. Of the “Stone Book of the Universe” we may say with truth that which Oliver Wendell Holmes says of the privately-interpreted Bible, namely, that its readers take from it the same views which they had previously brought to it. “I am, however, thoroughly persuaded,” say the late Yves Delage, “that one is or is not a transformist, not so much for reasons deduced from natural history, as for motives based on personal philosophic opinions. If there existed some other scientific hypothesis besides that of descent to explain the origin of species, many transformists would abandon their present opinion as not being sufficiently demonstrated.... If one takes his stand upon the exclusive ground of the facts, it must be acknowledged that the formation of one species from another species has not been demonstrated at all.” (“L’herédité et les grands problèmes de la biologie générale,” Paris, 1903, pp. 204, 322.)

II
THE PROBLEM OF ORIGINS

CHAPTER I
THE ORIGIN OF LIFE

§ 1. The Theory of Spontaneous Generation

Strictly speaking, the theory of Transformism is not concerned with the initial production of organic species, but rather with the subsequent differentiation and multiplication of such species by transmutation of the original forms. This technical sense, however, is embalmed only in the term transformism and not in its synonym evolution. The signification of the latter term is less definite. It may be used to denote any sort of development or origination of one thing from another. Hence the problem of the formation of organic species is frequently merged with the problem of the transformation of species under the common title of evolution.

This extension of the evolutionary concept, in its widest sense, to the problem of the origin of life on our globe is known as the hypothesis of abiogenesis or spontaneous generation. It regards inorganic matter as the source of organic life not merely in the sense of a passive cause, out of which the primordial forms of life were produced, but in the sense of an active cause inasmuch as it ascribes the origin of life to the exclusive agency of dynamic principles inherent in inorganic matter, namely, the physicochemical energies that are native to mineral matter. Life, in other words, is assumed to have arisen spontaneously, that is, by means of a synthesis and convergence of forces resident in inorganic matter, and not through the intervention of any exterior agency.

The protagonists of spontaneous generation, therefore, assert not merely a passive, but an active, evolution of living, from lifeless matter. As to the fact of the origin of the primal organisms from inorganic matter, there is no controversy whatever. All agree that, at some time or other, the primordial plants and animals emanated from inorganic matter. The sole point of dispute is whether they arose from inorganic matter by active evolution or simply by passive evolution. The passive evolution of mineral matter into plants and animals is an everyday occurrence. The grass assimilates the nitrates of the soil, and is, in turn, assimilated by the sheep, whose flesh becomes the food of man, and mineral substance is thus finally transformed into human substance. In the course of metabolic processes, the inorganic molecule may doff its mineral type and don, in succession, the specificities of plant, animal, and human protoplasm; and this transition from lower to higher degrees of perfection may be termed an evolution. It is an ascent of matter from the lowermost grade of an inert substance, through the intermediate grades of vegetative and animal life, up to the culminating and ultimate term of material perfection, in the partial constitution of a human nature and personality, in the concurrence as a coagent in vegetative and sensile functions, and in the indirect participation, as instrument, in the higher psychic functions of rational thought and volition.

At the present time, the inorganic world is clearly the exclusive source of all the matter found in living beings. All living beings construct their bodies out of inorganic substances in the process of nutrition, and render back to the inorganic world, by dissimilation and death, whatever they have taken from it. We must conclude, therefore, the matter of the primordial organisms was likewise derived from the inorganic world. But we are not warranted in concluding that this process of derivation was an active evolution. On the contrary, all evidence is against the supposition that brute matter is able to evolve of itself into living matter. It can, indeed, be transformed into plants, animals, and men through the action of an appropriate external agent (i.e. solely through the agency of the living organism), but it cannot acquire the perfections of living matter by means of its own inherent powers. It cannot vitalize, or sensitize, itself through the unaided activity of its own physicochemical energies. Only when it comes under the superior influence of preëxistent life can it ascend to higher degrees of entitive perfection. It does not become of itself life, sensibility, and intelligence. It must first be drawn into communion with what is already alive, before it can acquire life and sensibility, or share indirectly in the honors of intelligence (as the substrate of the cerebral imagery whence the human mind abstracts its conceptual thought). Apart from this unique influence, inorganic matter is impotent to raise itself in the scale of existence, but, if captured, molded, and transmuted by a living being, it may progress to the point of forming with the human soul one single nature, one single substance, one single person. The evolution of matter exemplified in organic metabolism is obviously passive, and such an evolution of the primal organisms out of non-living matter even the opponents of the hypothesis of spontaneous generation concede. But spontaneous generation implies an active evolution of the living from the lifeless, and this is the point around which the controversy wages. It would, of course, be utterly irrational to deny to the Supreme Lord and Author of Life the power of vivifying matter previously inanimate and inert, and hence the origin of organic life from inorganic matter by a formative (not creative) act of the Creator is the conclusion to which the denial of abiogenesis logically leads.

The hypothesis of spontaneous generation is far older than the theory of transformism. It goes back to the Greek predecessors of Aristotle, at least, and may be of far greater antiquity. It was based, as is well known, upon an erroneous interpretation of natural facts, which was universally accepted up to the close of the 17th century. As we can do no more than recount a few outstanding incidents of its long and interesting history here, the reader is referred to the VII chapter of Wasmann’s “Modern Biology” and the VIII chapter of Windle’s “Vitalism and Scholasticism” for the details which we are obliged to omit.

§ 2. The Law of Genetic Continuity—

From time immemorial the sudden appearance of maggots in putrescent meat had been a matter of common knowledge, and the ancients were misled into regarding the phenomenon as an instance of a de novo origin of life from dead matter. The error in question persisted until the year 1698, when it was decisively disproved by a simple experiment of the Italian physician Francesco Redi. He protected the meat from flies by means of gauze. Under these conditions, no maggots appeared in the meat, while the flies, unable to reach the meat, deposited their eggs on the gauze. Thus it became apparent that the maggots were larval flies, which emerged from fertilized eggs previously deposited in decaying meat by female flies. Antonio Vallisnieri, another Italian, showed that the fruit-fly had a similar life-history. As a result of these discoveries, Redi rejected the theory of spontaneous generation and formulated the first article of the Law of Genetic Vital Continuity: Omne vivum ex vivo.

Meanwhile, the first researches conducted by means of the newly invented compound microscope disclosed what appeared to be fresh evidence in favor of the discarded hypothesis. The unicellular organisms known as infusoria were found to appear suddenly in hay infusions, and their abrupt appearance was ascribed to spontaneous generation. Towards the end of the 18th century, however, a Catholic priest named Lazzaro Spallanzani refuted this new argument by sterilizing the infusions with heat and by sealing the containers as protection against contamination by floating spores or cysts. After the infusions had been boiled for a sufficient time and then sealed, no organisms could be found in them, no matter how long they were kept. We now know that protozoa and protophytes do not originate de novo in infusions. Their sudden appearance in cultures is due to the deposition of spores or cysts from the air, etc.

The possibility that the non-germination of life in sterilized infusions kept in sealed containers might be due to the absence of oxygen, removed by boiling and excluded by sealing, left open a single loophole, of which the 19th century defenders of abiogenesis proceeded to avail themselves. Pasteur, however, by employing sterilized cultures, which he aerated with filtered air exclusively, succeeded in depriving his opponents of this final refuge, and thereby completely demolished the last piece of evidence in favor of spontaneous generation. Prof. Wm. Sydney Thayer, in an address delivered at the Sorbonne, May 22, 1923, gives the following account of Pasteur’s experiments in this field: “Then, naturally (1860-1876) came the famous studies on spontaneous generation undertaken against the advice of his doubting masters, Biot and Dumas. On the basis of careful and well-conceived experiments he demonstrated the universal presence of bacteria in air, water, dust; he showed the variation in different regions of the bacterial content of the air; he demonstrated the permanent sterility of media protected from contamination, and he insisted on the inevitable derivation of every living organism from one of its kind. ‘No,’ he said, ‘there is no circumstance known today which justifies us in affirming that microscopic organisms have come into the world, without parents like themselves. Those who made this assertion have been the playthings of illusions or ill-made experiments invalidated by errors which they have not been able to appreciate or to avoid.’ In the course of these experiments he demonstrated the necessity of reliable methods of sterilization for instruments or culture media, of exposure for half an hour to moist heat at 120° or to dry air at 180°. And behold! our modern procedures of sterilization and the basis of antiseptic surgery.” (Science, Dec. 14, 1923, p. 477.) Pasteur brought to a successful completion the work of Redi and Spallanzani. Henceforth spontaneous generation was deprived of all countenance in the realm of biological fact.

Meanwhile, the cytologists and embryologists of the last century were adding article after article to the law of genetic cellular continuity, thus forging link by link the fatal chain of severance that inexorably debars abiogenesis from the domain of natural science. With the formulation of the great Cell Theory by Schleiden and Schwann (1838-1839), it became clear that the cell is the fundamental unit of organization in the world of living matter. It has proved to be, at once, the simplest organism capable of independent existence and the basic unit of structure and function in all the more complex forms of life. The protists (unicellular protozoans and protophytes) consist each of a single cell, and no simpler type of organism is known to science. The cell is the building brick out of which the higher organisms or metists (i.e. the multicellular and tissued metazoans and metaphytes) are constructed, and all multicellular organisms are, at one time or other in their career, reduced to the simplicity of a single cell (v.g. in the zygote and spore stages). The somatic or tissue cells, which are associated in the metists to form one organic whole, are of the same essential type as germ cells and unicellular organisms, although the parallelism is more close between the unicellular organism and the germ cell. The germ cell, like the protist, is equipped with all the potentialities of life, whereas tissue cells are specialized for one function rather than another. The protist is a generalized and physiologically-balanced cell, one which performs all the vital functions, and in which the suppression of one function leads to the destruction of all the rest; while the tissue cell is a specialized and physiologically-unbalanced cell limited to a single function, with the other vital functions in abeyance (though capable of manifesting themselves under certain circumstances). Normally, therefore, the tissue cell is functionally incomplete, a part and not a whole, whereas the protist is an independent individual, being, at once, the highest type of cell and the lowest type of organism.

According to the classic definition of Franz Leydig and Max Schultze, the cell is a mass of protoplasm containing a nucleus, both protoplasm and nucleus arising through division of the corresponding elements of a preëxistent cell. In this form the definition is quite general and applies to all cells, whether tissue cells, germ cells, or unicellular organisms. Moreover, it embodies two principles which still further determine the law of genetic cellular continuity, namely: Omnis cellula ex cellula, enunciated by Virchow in 1855, and Flemming’s principle: Omnis nucleus ex nucleo, proclaimed in 1882. In this way, Cytology supplemented Redi’s formula that every living being is from a preëxistent living being, by adding two more articles, namely, that every living cell is from a preëxistent cell, and every new cellular nucleus is derived by division from a preëxistent cellular nucleus. Now neither the nucleus nor the cell-body (the cytoplasm or extranuclear area of the cell) is capable of an independent existence. The cytoplasm of the severed nerve fibre, when it fails to reëstablish its connection with the neuron nucleus, degenerates. The enucleated amœba, though capable of such vital functions as depend upon destructive metabolism, can do nothing which involves constructive metabolism, and is, therefore, doomed to perish. The sperm cell, which is a nucleus that has sloughed off most of its cytoplasm, disintegrates, unless it regains a haven in the cytoplasm of the egg. Life, accordingly, cannot subsist in a unit more simply organized than the cell. No organism lives which is simpler than the cell, and the origin of all higher forms of life is reducible, as we shall see, to the origin of the cell. Consequently, new life can originate in no other way than by a process of cell-division. All generation or reproduction of new life is dependent upon the division of the cell-body and nucleus of a preëxistent living cell.

Haeckel, it is true, has attempted to question the status of the cell as the simplest of organisms, by alleging the existence of cytodes (non-nucleated cells) among the bacteria and the blue-green algæ. Further study, however, has shown that bacteria and blue-green algæ have a distributed nucleus, like that of certain ciliates, such as Dileptus gigas and Trachelocerca. In such forms the entire cell body is filled with scattered granules of chromatin called chromioles, and this diffuse type of nucleus seems to be the counterpart of the concentrated nuclei found in the generality of cells. At any rate, there is a temporary aggregation of the chromioles at critical stages in the life-cycle (such as cell-division), and these scattered chromatin granules undergo division, although their distribution to the daughter-cells is not as regular as that obtaining in mitosis. All this is strongly suggestive of their nuclear nature, and cells with distributed nuclei cannot, therefore, be classified as cytodes. In fact, the polynuclear condition is by no means uncommon. Paramœcium aurelia, for example, has a macronucleus and a micronucleus, and the Uroleptus mobilis has eight macronuclei and from two to four micronuclei. The difference between the polynuclear and diffuse condition seems to be relatively unimportant. In fact, the distributed nucleus differs from the morphological nucleus mainly in the absence of a confining membrane. From the functional standpoint, the two structures are identical. Hence the possession of a nucleus or its equivalent is, to all appearances, a universal characteristic of cells. Haeckel’s “cytodes” have proved to be purely imaginary entities. The verdict of modern cytologists is that Shultze’s definition of the cell must stand, and that the status of the cell as the simplest of organic units capable of independent existence is established beyond the possibility of prudent doubt.

With the progressive refinement of microscopic technique, it has become apparent that the law of genetic continuity applies not merely to the cell as a whole and to its major parts, the nucleus and the cell-body, but also to the minor components or organelles, which are seen to be individually self-perpetuating by means of growth and division. The typical cell nucleus, as is well known, is a spherical vesicle containing a semisolid, diphasic network of basichromatin (formerly “chromatin”) and oxychromatin (linin) suspended in more fluid medium or ground called nuclear sap. When the cell is about to divide, the basichromatin resolves itself into a definite number of short threads called chromosomes. Now, Boveri found that, in the normal process of cell-division known as mitosis, these nuclear threads or chromosomes are each split lengthwise and divided into two exactly equivalent halves, the resulting halves being distributed in equal number to the two daughter-cells produced by the division of the original cell. Hence, in the year 1903, Boveri added a fourth article to the law of genetic vital continuity, namely: Omne chromosoma ex chromosomate.

But the law in question applies to cytoplasmic as well as nuclear components. In physical appearance, the cell-body or cytoplasm resembles an emulsion with a clear semiliquid external phase called hyaloplasm and an internal phase consisting mainly of large spheres called macrosomes and minute particles called microsomes, all of which, together with numerous other formed bodies, are suspended in the clear hyaloplasm (hyaline ground-substance). Now certain of these cytoplasmic components have long been known to be self-perpetuating by means of growth and division, maintaining their continuity from cell to cell. The plastids of plant cells, for example, divide at the time of cell-division, although their distribution to the daughter-cells does not appear to be as definite and regular as that which obtains in the case of the chromosomes. Similarly, the centrioles or division-foci of animal cells are self-propagating by division, but here the distribution to the daughter-cells is exactly equivalent and not at random as in the case of plastids. In the light of recent research it looks as though two other types of cytoplasmic organelles must be added to the list of cellular components, which are individually self-perpetuating by growth and division, namely, the chondriosomes and the Golgi bodies—“both mitochondria and Golgi bodies are able to assimilate, grow, and divide in the cytoplasm.” (Gatenby.) Wilson is of opinion that the law of genetic continuity may have to be extended even to those minute granules and particles of the cytosome, which were formerly thought to arise de novo in the apparently structureless hyaloplasm. Speaking of the emulsified appearance of the starfish and sea urchin eggs, he tells us that their protoplasm shows “a structure somewhat like that of an emulsion, consisting of innumerable spheroidal bodies suspended in a clear continuous basis or hyaloplasm. These bodies are of two general orders of magnitude, namely: larger spheres or macrosomes rather closely crowded and fairly uniform in size, and much smaller microsomes irregularly scattered between the macrosomes, and among these are still smaller granules that graduate in size down to the limit of vision with any power (i.e. of microscope) we may employ.” (Science, March 9, 1923, p. 282.) Now, the limit of microscopic vision by the use of the highest-power oil-immersion objectives is one-half the length of the shortest waves of visible light, that is, about 200 submicrons (the submicron being one millionth of a millimeter). Particles whose diameter is less than this cannot reflect a wave of light, and are, therefore, invisible so far as the microscope is concerned. By the aid of the ultramicroscope, however, we are enabled to see the halos formed by particles not more than four submicrons in diameter, which, however, represents the limit of the ultramicroscope, and is the diameter hypothetically assigned to the protein multimolecule. Since, therefore, we find the particles in the protoplasm of the cell body graduating all the way down to the limit of this latter instrument, and since on the very limit of microscopic vision we find such minute particles as the centrioles “capable of self-perpetuation by growth and division, and of enlargement to form much larger bodies,” we cannot ignore the possibility that the ultramicroscopic particles may have the same powers and may be the sources or “formative foci” of the larger formed bodies, which were hitherto thought to arise de novo.

Certainly, pathology, as we shall see, tells us of ultramicroscopic disease-germs, which are capable of reproduction and maintenance of a specific type, and experimental genetics makes us aware of a linear alignment of submicroscopic genes in the nuclear chromosomes, each gene undergoing periodic division and perpetual transmission from generation to generation. The cytologist, therefore, to quote the words of Wilson, “cannot resist the evidence that the appearance of a simple homogeneous colloidal substance is deceptive; that it is in reality a complex, heterogeneous, or polyphasic system. He finds it difficult to escape the conclusion, therefore, that the visible and the invisible components of the protoplasmic system differ only in their size and degree of dispersion; that they belong to a single continuous series, and that the visible structure of protoplasm may give us a rough magnified picture of the invisible.” (Ibidem, p. 283.)

It would seem, therefore, that we must restore to honor, as the fifth article of the law of cellular continuity, the formula, which Richard Altmann enunciated on purely speculative grounds in 1892, but which the latest research is beginning to place on a solid factual basis, namely: Omne granulum ex granulo. “For my part,” says the great cytologist, Wilson, “I am disposed to accept the probability that many of these particles, as if they were submicroscopical plastids, may have a persistent identity, perpetuating themselves by growth and multiplication without loss of their specific individual type.” And he adds that the facts revealed by experimental embryology (e.g., the existence of differentiated zones of specific composition in the cytoplasm of certain eggs) “drive us to the conclusion that the submicroscopical components of the hyaloplasm are segregated and distributed according to an ordered system.” (Ibidem, p. 283.) The structure of the cell has often been likened to a heterogeneous solution, that is, to a complex polyphasic colloidal system, but this power of perpetual division and orderly assortment possessed by the cell as a whole and by its single components is the unique property of the living protoplasmic system, and is never found in any of the colloidal systems known to physical chemistry, be they organic or inorganic.

Cells, then, originate solely by division of preëxistent cells and even the minor components of the cellular system originate in like fashion, namely: by division of their respective counterparts in the preëxistent living cell. Here we have the sum and substance of the fivefold law of genetic continuity, whose promulgation has relegated the hypothesis of spontaneous generation to the realms of empty speculation. Waiving the possibility of an a priori argument, by which abiogenesis might be positively excluded, there remains this one consideration, which alone is scientifically significant, that, so far as observation goes and induction can carry us, the living cell has absolute need of a vital origin and can never originate by the exclusive agency of the physicochemical forces native to inorganic matter. If organic life exists in simpler terms than the cell, science knows nothing of it, and no observed process, simple or complicated, of inorganic nature, nor any artificial synthesis of the laboratory, however ingenious, has ever succeeded in duplicating the wonders of the simplest living cell.

§ 3. Chemical Theories of the Origin of Life

In fact, the very notion of a chemical synthesis of living matter is founded on a misconception. It would, indeed, be rash to set limits to the chemist’s power of synthesizing organic compounds, but living protoplasm is not a single chemical compound. Rather it is a complex system of compounds, enzymes and organelles, coördinated and integrated into an organized whole by a persistent principle of unity and finality. Organic life, to say nothing at all of its unique dynamics, is a morphological as well as a chemical problem; and, while it is conceivable that the chemist might synthesize all the compounds found in dead protoplasm, to reproduce a single detail of the ultramicroscopic structure of a living cell lies wholly beyond his power and province. “Long ago,” says Wilson (in the already quoted address on the “Physical Basis of Life”), “it became perfectly plain that what we call protoplasm is not chemically a single substance. It is a mixture of many substances, a mixture in high degree complex, the seat of varied and incessant transformations, yet one which somehow holds fast for countless generations to its own specific type. The evidence from every source demonstrates that the cell is a complex organism, a microcosm, a living system.” (Science, March 9, 1923, p. 278.)

With the chemist, analysis must precede synthesis, and it is only after a structural formula has been determined by means of quantitative analysis supplemented by analogy and comparison, that a given compound can be successfully synthesized. But living protoplasm and its structures elude such analysis. Intravitous staining is inadequate even as a means of qualitative analysis, and tests of a more drastic nature destroy the life and organization, which they seek to analyze. “With one span,” says Amé Pictet, Professor of Chemistry at the University of Geneva, “we will now bridge the entire distance separating the first products of plant assimilation from its final product, namely, living matter. And it should be understood at the outset that I employ this term ‘living matter’ only as an abbreviation, and to avoid long circumlocution. You should not, in reality, attribute life to matter itself; it has not, it cannot have both living molecules and dead molecules. Life requires an organization, which is that of cellular structure, but it remains, in contradistinction to it, outside the domain of strict chemistry. It is none the less true that the content of a living cell must differ in its chemical nature from the content of a dead cell. It is entirely from this point of view that the phenomenon of life pertains to my subject.... A living cell, both in its chemical composition and in its morphological structure, is an organism of extraordinary complexity. The protoplasm that it incloses is a mixture of very diverse substances. But if there be set aside on the one hand those substances which are in the process of assimilation and on the other those which are the by-products of nutrition, and which are in the process of elimination, there remain the protein or albuminous substances, and these must be considered, if not the essential factor of life, at least the theater of its manifestations.... Chemistry, however, is totally ignorant, or nearly so, of the constitution of living albumen, for chemical methods of investigation at the very outset kill the living cell. The slightest rise in temperature, contact with the solvent, the very powerful effect of even the mildest reactions cause the transformation that needs to be prevented, and the chemist has nothing left but dead albumen.” (Smithson. Inst. Rpt. for 1916, pp. 208, 209.)

Chemical analysis associated with physical analysis by means of the polariscope, spectroscope, x-rays, ultramicroscope, etc. is extremely useful in determining the structure of inorganic units like the atom and the molecule. Both, too, throw valuable light on the problem of the structure of non-living multimolecules such as the crystal units of crystalloids and the ultramicrons of colloids, but they furnish no clue to the submicroscopical morphology of the living cell. Such methods do not enable us to examine anything more than the “physical substrate” of life, and that, only after it has been radically altered; for it is not the same after life has flown. At all events, the integrating principle, the formative determinant, which binds the components of living protoplasm into a unitary system, which makes of them a single totality instead of a mere sum or fortuitous aggregate of disparate and uncoördinated factors, and which gives to them a determinate and persistent specificity that can hold its own amid a perpetual fluxion of matter and continual flow of energy, this is forever inaccessible to the chemist, and constitutes a phenomenon of which the inorganic world affords no parallel.

With these facts in mind, we can hardly fail to be amused whenever certain simple chemical reactions obtained in vitro are hailed as “clue to the origin of life.” When it was found, for instance, that, under certain conditions, an aldehyde (probably formaldehyde) is formed in a colloidal solution of chlorophyll in water, if exposed to sunlight, the discovery gave rise to Bach’s formaldehyde-hypothesis; for Alexis Bach saw in this reaction “a first step in the origin of life.” As formaldehyde readily undergoes aldol condensation into a syrupy fluid called formose, when a dilute aqueous solution of formaldehyde is saturated with calcium hydroxide and allowed to stand for several days, there was no difficulty in conceiving the transition from formaldehyde to the carbohydrates; for formose is a mixture containing several hexose sugars, and Fischer has succeeded in isolating therefrom acrose, a simple sugar having the same formula as glucose, namely: C₆H₁₂O₆. Glyceraldehyde undergoes a similar condensation. In view of these facts, carbohydrate-production in green plants was interpreted as a photosynthesis of these substances from water and carbon dioxide, with chlorophyll acting a sensitizer to absorb the radiant energy necessary for the reaction. The first step in the process was thought to be a reduction of carbonic acid to formic acid and then to formaldehyde, the latter being at once condensed into glucose, which in turn was supposed to be dehydrated and polymerized into starch. From the carbohydrates thus formed and the nitrates of the soil the plant could then synthesize proteins, while oxidation of the carbohydrates into fatty acids would lead to the formation of fats. Hence Bach regarded the formation of formaldehyde in the presence of water, carbon dioxide, chlorophyll, and sunlight as the “first step in the production of life.” Bateson, however, does not find the suggestion a very helpful one, and evaluates it at its true worth in the following contemptuous aside: “We should be greatly helped,” he says, “by some indication as to whether the origin of life has been single or multiple.” Modern opinion is, perhaps, inclined to the multiple theory, but we have no real evidence. Indeed, the problem still stands outside the range of scientific investigation, and when we hear the spontaneous formation of formaldehyde mentioned as a possible first step in the origin of life, we think of Harry Lauder in the character of a Glasgow schoolboy pulling out his treasures from his pocket—“That’s a wassher—for makkin’ motor cars.” (“Presidential Address,” cf. Smithson. Inst. Rpt. for 1915, p. 375.)

Bach, moreover, takes it for granted that the formation of formaldehyde is really the first step in the synthesis performed by the green plant, and he claims that formaldehyde is formed when carbon dioxide is passed through a solution of a salt of uranium in the presence of sunlight. Fenton makes a similar claim in the case of magnesium, asserting that traces of formaldehyde are discernible when metallic magnesium is immersed in water saturated with carbon dioxide. But at present it begins to look as though the spontaneous formation and condensation of formaldehyde had nothing to do with the process that actually occurs in green plants. Certain chemists, while admitting that an aldehyde is formed when chlorophyll, water, and air are brought together in the presence of sunlight, deny that the aldehyde in question is formaldehyde, and they also draw attention to the fact that this aldehyde may be formed in an atmosphere entirely destitute of carbon dioxide. In fact, the researches conducted by Willstätter and Stoll, and later (in 1916) by Jörgensen and Kidd tend to discredit the common notion that carbohydrate-production in plants is the result of a direct union of water and carbon dioxide. Botany textbooks still continue to parrot the traditional view. We cannot any longer, however, be sure but that the term photosynthesis may be a misnomer.

Carbohydrate-formation in plants seems to be more analogous to carbohydrate-formation in animals than was formerly thought to be the case. In animals, as is well known, glycogen or animal starch is formed not by direct synthesis, but by deämination and reduction of proteins. In a similar way, it is thought that the production of carbohydrates in plants may be due to a breaking down of the phytyl ester in chlorophyll, the chromogen group functioning (under the action of light) alternately as a dissociating enzyme in the formation of sugars and a synthesizing enzyme in the reconstruction of chlorophyll. Phytol is an unsaturated alcohol obtained when chlorophyll is saponified by means of caustic alkalis. Its formula is C₂₀H₃₉OH, and chlorophyll consists of a chromogen group containing magnesium (MgN₄C₃₂H₃₀O) united to a diester of phytyl and methyl alcohols.

Experimental results are at variance with the theory that chlorophyll acts as a sensitizer in bringing about a reduction of carbonic acid, after the analogy of eosin, which in the presence of light accelerates the decomposition of silver salts on photographic plates. Willstätter found that, when a colloidal solution of the pure extract of chlorophyll in water is exposed to sunlight and an atmosphere consisting of carbon dioxide exclusively, no formaldehyde is formed, but the chlorophyll is changed into yellow phæophytin owing to the removal of the magnesium from the chromogen group by the action of the carbonic acid. Jörgensen, on the other hand, discovered that in an atmosphere of pure oxygen, formaldehyde is formed, apparently by the splitting off and reduction of the phytyl ester of chlorophyll. Soon, however, the formaldehyde is oxidized to formic acid, which replaces the chlorophyllic magnesium with hydrogen, thus causing the green chlorophyll to degenerate into yellow phæophytin and finally to lose its color altogether. The dissociation of the chromogen group may be due to the fact that the reaction takes place in vitro, and may not occur in the living plant. At all events, it would seem that plants, like animals, manufacture carbohydrates by a destructive rather than a constructive process, and that water and carbon dioxide serve rather as materials for the regeneration of chlorophyll than as materials out of which sugars are directly synthesized.

A new theory has been proposed by Dr. Oskar Baudisch, who seems to have sensed the irrelevance of the formaldehyde hypothesis, and to have sought another solution in connection with the chromogen group of chlorophyll. He finds a more promising starting-point in formaldoxime, which, he claims, readily unites with such metals as magnesium and iron and with formaldehyde, in the presence of light containing ultra-violet rays, to form organic compounds analogous to the chromogen complexes in chlorophyll and hæmoglobin. Oximes are compounds formed by the condensation of one molecule of an aldehyde with one molecule of hydroxylamine (NH₂OH) and the elimination of a molecule of water. Hence Dr. Baudisch imagines that, given formaldoxime (H₂C:N·OH), magnesium, and ultra-violet rays, we might expect a spontaneous formation of chlorophyll leading eventually to the production of organic life. “It is his theory that life may have been caused through the direct action of sunlight upon water, air, and carbon dioxide in the ancient geologic past when, he believes, sunlight was more intense and contained more ultra-violet light and the air contained more water vapor and carbon dioxide than at the present time.” (Science, April 6, 1923, Supplement XII.)

This is the old Spencerian evasion, the fatuous appeal to “conditions unlike those we know,” the unverified and unverifiable assumption that an unknown past must have been more favorable to spontaneous generation than the known present. In archæozoic times, the temperature was higher, the partial pressure of atmospheric carbon dioxide greater, the percentage of ultra-violet rays in sunlight larger. Such contentions are interesting, if true, but, for all that, they may, “like the flowers that bloom in the spring,” have nothing to do with the case. Nature does not, and the laboratory cannot, reproduce the conditions which are said to have brought about the spontaneous generation of formaldoxime and its progressive transmutation into phycocyanin, chlorophyll and the blue-green algæ. What value, then, have these conjectures? If it be the function of natural science to discount actualities in favor of possibilities, to draw arguments from ignorance, and to accept the absence of disproof as a substitute for demonstration, then the expedient of invoking the unknown in support of a speculation is scientifically legitimate. But, if the methods of science are observation and induction, if it proceeds according to the principle of the uniformity of nature, and does not utterly belie its claim of resting upon factual realities rather than the figments of fancy, then all this hypothecation, which is so flagrantly at variance with the actual data of experience and the unmistakable trend of inductive reasoning, is not science at all, but sheer credulity and superstition.

When we ask by what right men of science presume to lift the veil of mystery from a remote past, which no one has observed, we are told that the justification of this procedure is the principle of the uniformity of nature or the invariability of natural laws. Nature’s laws are the same yesterday, today, and forever. Hence the scientist, who wishes to penetrate into the unknown past, has only to “prolong the methods of nature from the present into the past.” (Tyndall.) If we reject the soundness of this principle, we automatically cut ourselves off from all certainty regarding that part of the world’s history which antecedes human observation. Either nature’s laws change, or they do not. If they never change, then Spontaneous Generation is quite as much excluded from the past as it is from the present. If, however, as Hamann and Fechner explicitly maintain, nature’s laws do change, then, obviously, no knowledge whatever is possible respecting the past, since it is solely upon the assumption of the immutable constancy of such laws that we can venture to reconstruct prehistory.

The puerile notion that the synthesis of organic substances in the laboratory furnishes a clue to the origin of organic life on earth is due to a confusion of organic, with living and organized, substances. It is only in the production of organic substances that the chemist can vie with the plant or animal. These are lifeless and unorganized carbon compounds, which are termed organic because they are elaborated by living organisms as a metaplastic by-product of their metabolism. Such substances, however, are not to be confounded with animate matter, e.g. a living cell and its organelles, or even with organized matter, e.g. dead protoplasm. These the chemist cannot duplicate; for vitality and organization, as we have seen, are things that elude both his analysis and his synthesis. Even with respect to the production of organic substances, the parallelism between the living cell and the chemical laboratory is far from being a perfect one. Speaking of the metaplastic or organic products of cells, Benjamin Moore says: “Most of these are so complex that they have not yet been synthesized by the organic chemist; nay, even of those that have been synthesized, it may be remarked that all proof is wanting that the syntheses have been carried out in identically the same fashion and by the employment of the same forms of energy in the case of the cell as in the chemist’s laboratory. The conditions in the cell are widely different, and at the temperature of the cell and with such chemical materials as are at hand in the cell no such organic syntheses have been artificially carried out by the forms of energy extraneous to living tissue.” (“Recent Advances in Physiology and Bio-Chemistry,” p. 10.) Be that as it may, however, the prospect of a laboratory synthesis of an organic substance like chlorophyll affords no ground whatever for expecting a chemical synthesis of living matter. The chlorophyllic tail is inadequate to the task of wagging the dog of organic life. In this connection, Yves Delage’s sarcastic comment on Schaaffhausen’s theory is worthy of recall. The latter had suggested (in 1892) that life was initiated by a chemical reaction, in which water, air, and mineral salts united under the influence of light and heat to produce a colorless Protococcus, which subsequently acquired chlorophyll and became a Protococcus viridis. “If the affair is so simple,” writes Delage, “why does not the author produce a few specimens of this protococcus in his laboratory? We will gladly supply him with the necessary chlorophyll.” (“La structure du protoplasma et les théories sur l’hérédité,” p. 402.)

Another consideration, which never appears to trouble the visionaries who propound theories of this sort, is the fact that the inert elements and blind forces of inorganic nature are, if left to themselves, utterly impotent to duplicate even so much as the feats of the chemical laboratory, to say nothing at all of the more wonderful achievements possible only to living organisms. In the laboratory, the physicochemical forces of the mineral world are coördinated, regulated, and directed by the guiding intelligence of the chemist. In that heterogeneous conglomerate, which we call brute matter, no such guiding principle exists, and the only possible automatic results are those which the fortuitous concurrence of blind factors avails to produce. Chance of this kind may vie with art in the production of relatively simple combinations or systems, but where the conditions are as complex as those, which the synthesis of chlorophyll presupposes, chance is impotent and regulation absolutely imperative. How much more is this true, when there is question of the production of an effect so complicatedly telic as the living organism! “I venture to think,” says Sir William Tilden, in a letter to the London Times (Sept. 10, 1912), “that no chemist will be prepared to suggest a process by which, from the interaction of such materials (viz., inorganic substances), anything approaching a substance of the nature of a proteid could be formed or, if by a complex series of changes a compound of this kind were conceivably produced, that it would present the characters of living protoplasm.” In the concluding sentence of his letter, the great chemist seems to deprecate even the discussion of a chemical synthesis of living matter, whether spontaneous or artificial. “Far be it from any man of science,” he says, “to affirm that any given set of phenomena is not a fit subject of inquiry and that there is any limit to what may be revealed in answer to systematic and well-directed investigation. In the present instance, however, it appears to me that this is not a field for the chemist nor one in which chemistry is likely to afford any assistance whatever.” In any case, the idea that a chaos of unassorted elements and undirected forces could succeed where the skill of the chemist fails is preposterous. No known or conceivable process, or group of processes, at work in inorganic nature, is equal to the task. Chance is an explanation only for minds insensible to the beauty and order of organic life.

Darwin inoculated biological science with this Epicurean metaphysics, when, in his “Origin of Species,” he ascribed discriminating and selective powers of great delicacy and precision to the blind factors of a heterogeneous and variable environment. He compared natural selection to artificial selection, and in so doing, he was led astray by a false implication of his own analogy—“I have called this principle,” he says, “by which each slight variation, if useful, is preserved, by the term natural selection, in order to mark its relation to man’s power of selection.” (“Origin of Species,” 6th ed., c. III, p. 58.) Having likened the unintelligent and fortuitous selection and elimination exercised by the environment to the intelligent and purposive selection and elimination practiced by animal breeders and horticulturists, he pressed the analogy to the unwarranted extent of attributing to a blind, lifeless, and impersonal aggregate of minerals, liquids, and gases superhuman powers of discretion. To preserve even the semblance of parity, he ought first to have expurgated the process of artificial selection by getting rid of the element of human intelligence, which lurks therein, and vitiates its parallelism with the unconscious and purposeless havoc wrought at random by the blind and uncoördinated agencies of the environment. If inorganic nature were a vast and multifarious mold, a preformed sieve with holes of different sizes, a separator for sorting coins of various denominations, Darwin’s idea would be, in some degree, defensible, but this would only transfer the problem of cosmic order and intelligence from the organism to the environment. As a matter of fact, the mechanism of the environment is far too simple in its structure and too general in its influence to account for the complexities and specificities of organisms, that is, for the morphology and specific differences of plants and animals. Hence the selective work of the environment is negligible in the positive sense, and consists, for the most part, in a tendency to eliminate the abnormal and the subnormal. On the other hand, the environment as well as the organism is fundamentally teleological, and the environmental mechanism, though simple and general, is nevertheless expressly preadapted for the maintenance of organic life. Henderson, the bio-chemist of Harvard, has shown conclusively, in his “Fitness of the Environment” (1913), that the environment itself has been expressly selected with this finality in view, and that the inorganic world, while not the active cause, is, nevertheless, the preördained complement of organic life.

Simple constructions may, indeed, be due to pure accident as well as deliberate art, inasmuch as they presuppose but few and easy conditions. Complex constructions, on the contrary, provided they be systematic and not chaotic, are not producible by accident, but only by art, because they require numerous and complicated conditions. Operating individually, the unconscious factors of inorganic nature can produce simple and homogeneous constructions such as crystals. Operating in uncoördinated concurrence with one another, these blind and unrelated agencies produce complex chaotic formations such as mountains and islands, mere heterogeneous conglomerates, destitute of any determinate size, shape, or symmetry, constructions in which every single item and detail is the result of factors each of which is independent of the other. In short, the efficacy of the unconscious and uncoordinated physicochemical factors of inorganic nature is limited to fortuitous results, which serve no purpose, embody no intelligible law, convey no meaning nor idea, and afford no æsthetic satisfaction, being mere aggregates or sums rather than natural units and real totalities. But it does not extend to the production of complex systematic formations such as living organisms or human artefacts. Left to itself, therefore, inorganic nature might conceivably duplicate the simplest artefacts such as the chipped flints of the savage, and it might also construct a complex heterogeneous chaos of driftwood, mud, and sand like the Great Raft of the Red River, but it would be utterly impotent to construct a complicated telic system comparable to an animal, a clock, or even an organic compound, like chlorophyll.

In this connection, it is curious to note how extremely myopic the scientific materialist can be, when there is question of recognizing a manifestation of Divine intelligence in the stupendous teleology of the living organism, and how incredibly lynx-eyed he becomes, when there is question of detecting evidences of human intelligence in the eoliths alleged to have been the implements of a “Tertiary Man.” In the latter case, he is never at a loss to determine the precise degree of chipping, at which an eolith ceases to be interpretable as the fortuitous product of unconscious processes, and points infallibly to the intelligent authorship of man, but he grows strangely obtuse to the psychic implications of teleology, when it comes to explaining the symmetry of a starfish or the beauty of a Bird of Paradise.

In conclusion, it is clear that the hypothesis of a spontaneous origin of organic life from inorganic matter has in its favor neither factual evidence nor aprioristic probability, but is, on the contrary, ruled out of court by the whole force of the scientific principle of induction. To recapitulate, there are no subcellular organisms, and all cellular organisms (which is the same as saying, all organisms), be they unicellular or multicellular, originate exclusively by reproduction, that is, by generation from living parents of the same organic type or species. This is the law of genetic vital continuity, which, by the way, Aristotle had formulated long before Harvey, when he said: “It appears that all living beings come from a germ, and the germ from parents.” (“De Generatione Animalium,” lib. I, cap. 17.) All reproduction, however, is reducible to a process of cell-division. That such is the case with unicellular organisms is evident from the very definition of a cell. That it is also true of multicellular organisms can be shown by a review of the various forms of reproduction occurring among plants and animals.

§ 4. Reproduction and Rejuvenation

Reproduction, the sole means by which the torch of life is relayed from generation to generation, the exclusive process by which living individuals arise and races are perpetuated, consists in the separation of a germ from the parent organism as a physical basis for the development of a new organism. The germ thus separated may be many-celled or one-celled, as we shall see presently, but the separated cells, be they one or many, have their common and exclusive source in the process of mitotic cell-division. In a few cases, this divisional power or energy of the cell seems to be perennial by virtue of an inherent inexhaustibility. In most cases, however, it is perennial by virtue of a restorative process involving nuclear reorganization. In the former cases, which are exceptional, the cellular stream of life appears to flow onward forever with steady current, but as a general rule it ebbs and flows in cycles, which involve a periodic rise and fall of divisional energy. The phenomena of the life-cycle are characteristic of most, perhaps all, organisms. The complete life-cycle consists of three phases or periods, namely: an adolescent period of high vitality, a mature period of balanced metabolism, and a senescent period of decline. Each life-cycle begins with the germination of the new organism and terminates with its death, and it is reproduction which constitutes the connecting link between one life-cycle and another.

Reproduction, as previously intimated, is mainly of two kinds, namely: somatogenic reproduction, which is less general and confined to the metists, and cytogenic reproduction, which is common to metists and protists, and which is the ordinary method by which new organisms originate. Reproduction is termed somatogenic, when the germ separated from the body of the parent consists of a whole mass of somatic or tissue cells not expressly set aside and specialized for reproductive purposes. Reproduction is termed cytogenic, when the germ separated from the parent or parents consists of a single cell (e.g. a spore, gamete, or zygote) dedicated especially to reproductive purposes.

Cytogenic reproduction may be either nonsexual (agamic) or sexual, according as the cell which constitutes the germ is an agamete or a gamete. An agamete is a germ cell not specialized for union with another complementary cell, or, in other words, it is a reproductive cell incapable of syngamy, e.g. a spore. A gamete, on the other hand, is a reproductive cell (germ cell) specialized for the production of a zygote (a synthetic or diploid germ cell) by union with a complementary cell, e.g. an egg, or a sperm.

Nonsexual cytogenic reproduction is of three kinds, according to the nature of the agamete. When a unicellular organism gives rise to two new individuals by simple cell-division, we have fissiparation or binary fission. When a small cell or bud is formed and separated by division from a larger parent cell, we have budding (gemmation) or unequal fission. When the nucleus of the parent cell divides many times to form a number of daughter-nuclei, which then partition the cytoplasm of the parent cell among themselves so as to form a large number of reproductive cells called spores, we have what is known as sporulation or multiple fission. The first and second kind of nonsexual reproduction are confined to the protists, but the third kind (sporulation) also occurs among the metists.

Sexual cytogenic reproduction is based upon gametes or mating germ cells. Since complementary gametes are specialized for union with each other to form a single synthetic cell, the zygote, the number of their nuclear threads or chromosomes is reduced to one half (the haploid number) at the time of maturation, so that the somatic or tissue cells of the parent organism have double the number (the diploid number) of chromosomes present in the reduced or mature gametes. Hence, when the gametes unite to form a zygote, summation is prevented and the diploid number of chromosomes characteristic of the given species of plant or animal is simply restored by the process of syngamy or union. The process by which the number of chromosomes is reduced in gametes is called meiosis, and, among the metists, it is distinct from syngamy, which, in their case, is a separate process called fertilization. Among the protists, we have, besides fertilization, another type of syngamy called conjugation, which combines meiosis with fertilization.

In sexual reproduction, we have three kinds of gametes, namely: isogametes, anisogametes, and heterogametes. In the type of sexual reproduction known as isogamy, the complementary gametes are exactly alike both in size and shape. There is no division of labor between them. Each of the fusing gametes is equally fitted for the double function which they must perform, namely, the kinetic function, which enables them to reach each other and unite by means of movement, and the trophic function which consists in laying up a store of food for the sustenance of the developing embryo. In anisogamy, the complementary gametes are alike in shape, but unlike in size, and here we have the beginning of that division of labor, upon which the difference of gender or sex is based. The larger or female gamete is called a macrogamete. It is specialized for the trophic rather than the kinetic function, being rendered more inert by having a large amount of yolk or nutrient material stored up within it. The smaller or male gamete is called a microgamete. It is specialized for the kinetic function, since it contains less yolk and is the more agile of the two. In anisogamy, however, the division of labor is not complete, because both functions are still retained by either gamete, albeit in differing measure. In the heterogamy, the differentiation between the male and female gametes is complete, and they differ from each other in structure as well as size. The larger or female gamete has no motor apparatus and retains only the trophic function. The kinetic function is sacrificed to the task of storing up a food supply for the embryo. Such a gamete is called a hypergamete or egg. The smaller or male gamete is known, in this case, as a hypogamete or sperm. It has a motor apparatus, but no stored-up nutrients, and has even sloughed off most of its cytoplasm, in its exclusive specialization for the motor function. In heterogamy, accordingly, the division of labor is complete.