The main ant.i.thesis at present is the following. On the one side, the "all-sufficiency of natural selection" is maintained, that is, progressive evolution is regarded as coming about without direct self-exertion on the part of the organisms themselves, simply through the fact that fortuitous variations are continually presenting themselves, and are being selected and established according to their utility in the struggle for existence.

On the other side-with Lamarck-the progress is regarded as due to effort and function on the part of the organism itself. (Increased use of an organ strengthens it; a changed use transforms it; disuse causes it to degenerate. Thus new characters appear, old ones pa.s.s away, and in the course of thousands of years the manifold diversity of the forms of life has been brought about.)

Further, by those of the one side variation is regarded as occurring by the smallest steps that could have selective value in the struggle for existence. To the others variation seems to have taken place by leaps and bounds, with relatively sudden transformations of the functional and structural equilibrium on a large scale. In regard to these the _role_ of the struggle for existence must be merely subsidiary. This saltatory kind of evolution-process is called "halmatogenesis," or, more neatly, "kaleidoscopic variation," because, as the pictures in a kaleidoscope change not gradually but by a sudden leap to an essentially new pattern, so also do the forms of life. a.s.sociated with this is the following contrast. One side believes in free and independent variation of any organ, any part, any function, physical or mental, any instinct, and so on, apart from change or persistence in the rest of the organism; the other side believes in the close connectedness of every part with the whole, in the strict "correlation" of all parts, in variation in one part being always simultaneously a.s.sociated with variation in many other parts, all being comprised in the "whole," which is above and before all the parts and determines them. And further, to one school variation seems without plan in all directions, simply plus or minus on either side of a mean; to the other, variation seems predetermined and in a definite direction-an "orthogenesis," in fact, which is inherent in the organism, and which is indifferent to utility or disadvantage, or natural selection, or anything else, but simply follows its prescribed path in obedience to innate law. The representatives of this last position differ again among themselves. Some regard it as true in detail, in regard, for instance, to the markings of a b.u.t.terfly's wing, the striping of a caterpillar, the development of spots on a lizard; while others regard it as governing the general process of evolution as a whole. Finally, there is the most important contrast of all. On the one side, subordination, pa.s.sivity, complete dependence on the selective or directive factors in evolution, which alone have any power; on the other, activity, spontaneous power of adaptation and transformation, the relative freedom of all things living, and-the deepest answer to the question of the controlling force in evolution-_the secret of life_. This last contrast goes deeper even than the one we have already noted, that between the Darwinian and the Lamarckian principle of explanation; and it leads ultimately from the special Darwinian problem to quite a new one, to be solved by itself-the problem of the nature and secret of living matter.

Weismannism.

In regard to almost all the points to which we have referred, the most consistent and decided champion of Darwinism in its essential principles is the zoologist of Freiburg, August Weismann.(35) In long chapters on the protective coloration of animals, on the phenomena of mimicry-that resemblance to foreign objects (leaves, pieces of wood, bark, and well-protected animals) by which the mimics secure their own safety from enemies-on the protective devices in plants, the selective value of "the useful" is demonstrated. In regard to the marvellous phenomena of "carnivorous" plants, the still more marvellous instincts of animals, which cannot be interpreted on Lamarckian lines as "inherited habit," but only as due to the c.u.mulative influence of selection on inborn tendencies, as well as in regard to "symbiosis," "the origin of flowers," and so on, he attempts to show that the heterodox attempts at explanation are insufficient, and that selection alone really explains. At the same time the Darwinian principle is carried still further. It is not only among the individuals, the "persons," that the selective struggle for existence goes on. Personal selection depends upon a "germinal selection" within the germ-plasm, influencing it, and being influenced by it-for instance, restrained.

In order to explain the mystery of heredity, Weismann long ago elaborated, in his germ-plasm theory, the doctrine that the developing individual is materially preformed, or rather predetermined in the "idants" and "ids" of the germ-cell. Thus every one of its physical characters (and, through these, its psychical characters), down to hairs, skin spots, and birth-marks, is represented in the "id" by "determinants" which control the "determinates" in development. In the course of their growth and development these determinants are subject to diverse influences due to the position they happen to occupy, to their quality, to changes in the nutritive conditions, and so on. Through these influences variations in the determinants may be brought about. And thus there comes about a "struggle" and a process of selection among the determinants, the result of which is expressed in changes in the determinates, in the direction of greater or less development. On this basis Weismann attempts to reach explanations of the phenomena of variation, of many apparently Lamarckian phenomena, and of recognised cases of "orthogenesis," and seeks to complete and deepen Roux's theory of the "struggle of parts," which was just another attempt to carry Darwinism within the organism.

What distinguishes Weismann, and makes him especially useful for our present purpose of coming to an understanding in regard to the theory of selection is, that his views are unified, definite and consistent. In his case we have not to clear up the ground and to follow things out to their conclusions, nor to purge his theories from irrelevant, vitalistic, or pantheistic accessory theories, as we have, for instance, in the case of Haeckel. His book, too, is kept strictly within its own limits, and does not attempt to formulate a theory of the universe in general, or even a new religion on the basis of biological theories. Let us therefore inquire what has to be said in regard to this clearest and best statement of the theory of selection when we consider it from the point of view of the religious conception of the world.

Whatever else may be said as to the all-sufficiency of natural selection there can be no doubt that it presupposes two absolute mysteries which defy naturalistic explanation and every other, and which are so important that in comparison with them the problem of the struggle for efficacy and its meaning fades into insignificance. These are the functions and capacities of living organisms in general, and in particular those of variation and inheritance, of development and self-differentiation. What is, and whence comes this mysterious power of the organism to build itself up from the smallest beginnings, from the germ? And the equally mysterious power of faithfully repeating the type of its ancestors? And, again, of varying and becoming different from its ancestors? Even the "mechanical"

theory of selection is forced to presuppose the secret of life. Weismann indeed attempts to solve this riddle through his germ-plasm theory, the predisposition of the future organism in the "ids," determinants, and biophors, and through the variation of the determinants in germinal selection, amphimixis and so on. But this is after all only shifting the problem to another place, and translating the mystery into algebraical terms, so to speak, into symbols with which one can calculate and work for a little, which formulate a definite series of observations, an orderly sequence of phenomena, which are, however, after all, "unknown quant.i.ties"

that explain nothing.

In order to explain the developing organism Weismann a.s.sumes that each of its organs or parts, or "independent regions," is represented in the germ-plasm by a determinant, upon the fate of which the development of the future determinate depends. It is thought of as a very minute corpuscle of living matter. Thus there are determinants of hairs and scales, pieces of skin, pits, marks, &c. But every determined organ, or part, or "independent region," is itself in its turn an "organism," is indeed a system of an infinite number of interrelated component parts, and each of these again is another, down to the individual cells. And each cell is an "organism" in itself, and so on into infinity. Is all this represented in the determinants? And how?

Further, the individual determinate, for instance of a piece of skin, is not something isolated, but pa.s.ses over without definite boundary into others. Therefore the determinants also cannot be isolated, but must be systems within systems, dependent upon and merging into one another. How, at the building up of the organism, do the determinants find their direction and their localisation? And, especially, how do they set to work to build up their organ? Here the whole riddle of the theory of epigenesis, which Weismann wished to do away with as a mystery, is repeated a thousand times and made more difficult. In order to explain puzzling processes on a large scale, others have been constructed, which on close investigation prove to be just the same mysterious and unexplained processes, only made infinitely smaller.

Moreover, even if the whole of "Weismannism," including germinal selection, could be accepted, and if it were as sufficient as it is insufficient, what we advanced at the end of Chapter III. as a standpoint of general validity in relation to teleology and theology would still hold good. Even an entirely nave, anthropomorphic, "supernatural" theology is ready to see, in the natural course of things, in the "_causae secundariae,_" the realisation of Divine purpose, teleology, and does not fail to recognise that the Divine purpose may fulfil itself not only in an extraordinary manner, through "miracles" and "unconditioned" events, but also in ordinary ways, "through means" and the universal causal nexus.

Thus it is quite consistent even with a theology of this kind to regard the whole system of causes and effects, which, according to the Darwin-Weismann doctrine, have gradually brought forth the whole diversity of the world of life, with man at its head, in a purely causal way without teleological intervention, as an immense system of means marvellous in its intricacy, in the inevitable necessity of its inter-relations, and in the exactness of its work, the ultimate result of which _must_ have come about, but perhaps at the same time was _intended_ to come about. Whether I regard this ultimate result as the mere consequence of blind happenings, or as an intended purpose, does not depend, as we have seen, upon the knowledge gained by natural science, but depends above all on whether this ultimate result seems to me of sufficient _value_ to be thought of as the purpose of a world-governing intelligence, and thus depends upon my personal att.i.tude to human nature, reason, mind, and the spiritual, religious, and moral life. If I venture to attribute worth, and absolute worth, to these things, nothing, not even the fact of the "struggle for existence" in its thousand forms, in its gradually transforming effects, in the almost endless nexus of its causes and results, germinal selection included, can take away my right (and eventually my duty) to regard the ultimate result _as an end_, and the nexus of causes as a system of means.

To enable me to do this, it is only requisite that internal necessity should govern the system, and that the result should not be a chance one, so that it might even have been suppressed, have failed, or have turned out quite differently. Necessity and predetermination are characteristic of the relation between means and purpose. But this requisite is precisely that which natural science does afford us,-namely, the proof that all phenomena are strictly governed by law, and are absolutely predetermined by their antecedents. At this point the religious and the scientific consideration coincide exactly. The hairs of our head, and the hairs in the fur of a polar bear, which is varying towards white, and is therefore selected in the struggle for existence,(36) even the fluctuating variations of a determinant in the germ, are "numbered" according to both conceptions. Every variation that cropped up, every factor that "selected"

the fit, and eliminated the unfit, was strictly predestined, and must of necessity have appeared as, and when, and where it did appear.(37)

The whole nexus of conditions and results, the inclined plane of evolution and the power of Being to move up it, has its sufficient reason in the nature and original state of the cosmos, in the const.i.tution of its "matter," its "energy," its laws, its sequences and the grouping of its phenomena. Only from beginnings so const.i.tuted could our present world have come to be as it is, and that necessarily. Only because the primary possibility and fitness for life-vegetable, animal and human-was in it from the beginning, could all these have come to be. This primary possibility did not "come into being," it was _a priori_ immanent in it.

Whence came this? There is no logical, comprehensible, or any other necessity why there should be a world at all, or why it should be such that life and evolution must become part of it. Where then lies the reason why it is, rather than is not, and why it is as it is?

To this must be added what Weismann himself readily admits and expressly emphasises. The whole theory treats, and must treat plant, animal, and man as only ingenious machines, mere systems of physical processes. This is the ideal aimed at-to interpret all the phenomena of life, growth, and reproduction thus. Even instincts and mental endowments are so interpreted, since there must be corresponding morphological variations of the fine structure of the nervous organ, and instinctive actions are then "explained" as the functions of these. But how "mechanical happening"

comes to have this marvellous inwardness, which we call sensation, feeling, perception, thought and will, which is neither mechanical nor derivable from anything mechanical; and, further, how physical and psychical can condition one another without doing violence to the law of the conservation of the sum of energy, is an absolute riddle. But this whole psychical world exists, with graduated stages perhaps as close to each other as in the physical world, but even less capable than these of being explained as having arisen out of their antecedent lower stages. And this psychical world, which is, indeed, related to and dependent upon the corporeal life, as also conversely, has its own quite peculiar laws: thought does not follow natural laws, but those of logic, which is entirely indifferent to exciting stimuli, for instance of the brain, which conform to natural laws. But this world, its riddles and mysteries, its great content and its history, beyond the reach of mechanical theories, is so absolutely the main thing (especially in regard to the question of the possibility of religion), that the question of bodily structure and evolution becomes beside it a mere accessory problem, and even the last is only a relatively unimportant roundabout way of coming at the gist of the business. How completely the evolution of the higher mental faculties transcends such narrow and meagre formulae as the struggle for existence and the like, Weismann himself indicates in connection with man's musical sense, and its relation to the "musical" instinct in animals. The same and much more might be alleged in regard to the whole world of mind, of the aesthetic, ethical and religious, of the kingdom of thought, of science, and of poetry.

Natural Selection.

We have for the moment provisionally admitted the theory of natural selection, in order to see whether it could be included in a religious interpretation of things. But in reality such an admission is not to be thought of, in face of what is at present so apparent-the breaking down of this hypothesis, which has been upheld with so much persistence. We shall have to occupy ourselves with this later on. In the meantime a few more remarks must be added to what has been already said.

It might be said, paradoxically, that the worst fate that could befall this hypothesis would be to be proved, for then it would be most certainly refuted. What we mean is this: If it is really "utility" that rules the world and things, there can be no certainty and objectivity of knowledge, no guarantee of truth. The "struggle for existence" is not concerned with selecting beings who see the world as it is. It selects only the interpretation and conception of the environment that is most serviceable for the existence and maintenance of the species. But there is nothing to guarantee that the "true" knowledge will also be the most useful. It might quite well be that an entirely subjective and in itself wholly false interpretation would be the most serviceable. And if, by some extraordinary chance, the selected interpretation should be also the true one, there would be no means of establishing the fact. And what is true of this interpretation is true also of all theories that are derived from it, for example of the theory of selection itself.

Furthermore, a great part, perhaps the greatest part of the confidence placed in the theory of selection is due to an involuntary, but entirely fallacious habit of crediting it with the probabilities in favour of the doctrine of descent. The main arguments in favour of evolution and descent are very often, though unwittingly, adduced in support of Darwinism in particular. This is a great mistake. Take, for instance, the evidence of the "palaeontological" record. It affords hundreds of proofs of evolution, but not a single proof of selection. Its "intermediate" and "connecting links" do possibly prove the affiliation of species and the validity of genealogical trees. But precisely the "intermediate links" which _selection_ requires-the myriads of forms of life which were not successfully adapted, the unfit compet.i.tors in the struggle for existence which must have accompanied the favourably adapted variants from step to step, from generation to generation-these are altogether awanting.

Another circ.u.mstance seems to us to have been entirely overlooked, and it is one which gives the theory of selection an inevitable appearance of truth, even if it is essentially false, and thus makes it very difficult to refute. a.s.suming that the recognition of teleological factors is valid, that there is an inward law of development, that "Moses" or whoever one will was undoubtedly right, it is self-evident that, because of the indubitable over-production of organisms, there would even then be a struggle for existence on an immense scale, and that it would have a far-reaching "selective" influence, because of the relative plasticity of many forms of life. Beyond doubt it would, in the course of aeons, have applied its shears to many forms of life, and probably there would be no organisms, organs, or a.s.sociations in the evolution of the ultimate form of which it had not energetically co-operated. Its influence would, perhaps, be omnipresent, yet it might be far from being the all-sufficient factor in evolution; indeed, as far as the actual impulse of evolution is concerned, it might be a mere accessory. Unless we are to think of the forms of life as wholly pa.s.sive and wooden, the struggle for existence must necessarily be operative, and the magnitude of its results, and their striking and often bizarre outcome, will tend ever anew to conceal the fact that the struggle is after all only an inevitable accompaniment of evolution. And thus we understand how it is that interpretations from the point of view of an inward law of development, of orthogenesis, or of teleology, notwithstanding their inherent validity, have _a priori_ always had a relatively difficult position as compared with the Darwinian view.

It is usual to speak of the "all-sufficiency of natural selection," yet the champion of the selection-theory admits, as he needs must, that the struggle for existence and selection can of themselves create absolutely nothing, no new character, no new or higher combination of the vital elements; they can only take what is already given; they can only select and eliminate among the wealth of what is offered.(38) And the offerer is Life itself by virtue of its mysterious capacity for boundless and inexhaustible variability, self-enrichment and increase. The "struggle for existence" only digs the bed through which life's stream flows, draws the guiding-line, and continually stimulates it to some fresh revelation of its wealth. But this wealth was there from the beginning; it was, to use the old word, "potential" in the living, and included with it in the universal being from which life was called forth. The struggle for existence is only the steel which strikes the spark from the flint; is, with its infinite forms and components, only the incredibly complex channel through which life forces its way upwards. If we keep this clearly in mind, the alarming and ominous element in the theory shrinks to half its dimensions.

And, finally, if we can rid ourselves of the peculiar fascination which this theory exercises, we soon begin to discover what extraordinary improbability and fundamental artificiality it implies. "Utility" is maintained to be that which absolutely, almost tyrannically, determines form and development in the realm of the living. Is this an idea that finds any a.n.a.logy elsewhere in nature? Those who uphold the theory most strongly are wont to compare the development of organisms to crystal-formation in order in some way to tack on the living to the not-living. Crystal-formation, with its processes of movement and form-development, is, they say, a kind of connecting link between the living and the not-living. And in truth we find here, as in the realm of life, species-formation, development into individuals, stages and systems.

But all this takes place without any hint of "struggle for existence," of laboriously "selective" processes, or of ingenious acc.u.mulation of "variations." The "species" of crystals are formed not according to utility, but according to inherent, determining laws of development, to which the diversity of their individual appearances is due. If "Life" were only a higher potential of what is already stirring in crystallisation, as this view suggests, then we should expect to find fixed tendencies, determined from within, in accordance with which life would pa.s.s through the cycle of its forms and possibilities, and rise spontaneously through gradual stages.

CHAPTER VII. CRITICS OF DARWINISM.

Let us turn now to the other side. What is opposed to Darwinism in the biological investigations of the experts of to-day is in part simple criticism of the Darwinian position as a whole or in some of its details, and in part constructive individual theories and interpretations of the evolution of organisms.

A. Fleischmann's book, "Die Darwinsche Theorie,"(39) is professedly only critical. He suggests no theory of his own as to the evolution of life in contrast to Darwin's; for, as we have already seen in connection with his earlier book, "Die Deszendenztheorie," he denies evolution altogether. His agnostic position is maintained, if possible, more resolutely than before.

Natural science, according to him, must keep to facts. Drawing conclusions and spinning theories is inexact, and distracts from objective study. The Darwinian theory of selection seems to him a particularly good example of this, for it is built up _a priori_ on theories and hypotheses, it stands apart from experimentation, and it twists facts forcibly to its own ends.

It has, however, to be acknowledged that Fleischmann's book is without any "apologetic" intentions. It holds equally aloof from teleology. To seek for purposes and aims in nature he holds to be outside the business of science, as Kant's "Critique of Judgment" suffices to show. After having been more than a decade under the charm of the theory of selection, Fleischmann knows its fascination well, but he now regards it as so erroneous that no one who wishes to do serious work should concern himself about it at all. Point by point he follows all the details of Darwin's work, and seeks to a.n.a.lyse the separate views and theories which go to make up Darwinism as a whole. Darwin's main example of the evolution of the modern races of pigeons from one ancestral form, _Columba livia_, is, according to Fleischmann, not only unproved but unprovable.(40) For this itself is not a unified type. The process of "unconscious selection" by man is obscure, and it is not demonstrable, especially in regard to pigeon-breeding. It is a hazy idea which cannot be transferred to the realm of nature. The Malthusian a.s.sumption of the necessity of the struggle for existence is erroneous. Malthus was wrong in his law of population as applied to human life, and Darwin was still more mistaken when he transferred it to the organic world in general. It was mere theory. Statistics should have been collected, and observations instead of theories should have been sought for. The alleged superabundance of organisms is not a fact. The marvellously intertwined conditions in the economy of nature make the proportion of supply and demand relatively constant. And even when there is actual struggle for existence, advantages of situation,(41) which are quite indifferent as far as selection is concerned, are much more decisive than any variational differences. The theory does not explain the first origin of new characters, which can only become advantageous when they have attained to a certain degree of development. As to the ill.u.s.trations of the influence of selection given by Darwin, from the much discussed fict.i.tious cases, in which the fleet stags select the lithe wolf, to the marvellous mutual adaptations of insects and flowers, Fleischmann objects that there is not even theoretical justification for any one of them. The spade-like foot of the mole is not "more useful" than the form of foot which probably preceded it (_cf._ Goette), it is merely "different." For when the mole took to burrowing in the earth and adapting itself to that mode of life, it _ipso facto_ forfeited all the advantages of living above ground. The postulated myriads of less well-adapted forms of life are no more to be found to-day than they are in the fauna and flora of palaeontological times. The famous giraffe story has already been disposed of by Mivart's objections. As to the whales, it is objected that the earliest stages of their whalebone and their exaggerated nakedness can have been of no use, and a series of other alleged selective effects of "utility" are critically a.n.a.lysed. The refutation of the most brilliant chapter in the Darwinian theory, that on protective coloration and mimicry, is very insufficient. A long concluding chapter sums up the fundamental defects of the Darwinian theory.

For the most part, Fleischmann simply brings forward objections which have been urged against the theory of selection from the first, either by naturalists or from other quarters. The chief and the most fatal of these which are still current are the following: The theory of selection does not explain the actually existing discontinuity of species. The real characteristics which distinguish species from species are in innumerable cases quite indifferent from the point of view of "utility" (Nageli, Bateson). "Selection preserves the good and weeds out the bad." But where does the good come from? (De Vries). The first beginnings of what may later be useful are almost always useless. The theory of selection might perhaps explain the useful qualities, but not the superfluous, useless, or directly injurious characters which actually exist. Confirmation of the theory of descent may be found in the palaeontological record, but it affords none of the theory of selection. Natural selection is continually being neutralised by subsequent inter-crossing and reversion. Natural selection may indeed prevent degeneration within the limits of the species by weeding out what is weak and bad, but it is powerless beyond these limits, and so forth.(42)

These ever-repeated and ever-increasing objections are purely critical. As this is true of Fleischmann's whole book, it is therefore unsatisfactory.

It leaves everything in the mist, and puts nothing in place of what it attempts to demolish. But attempts are being made in other quarters, especially among the Lamarckians, to build up an opposition theory.

Lamarckism and Neo-Lamarckism.

The "Lamarckian" view as opposed to the Darwinian continues to hold its own, and indeed is more ardently supported than ever. On this view, evolution has been accomplished not by a laborious selection of the best which chanced to present itself-a selection in relation to which organisms remained pa.s.sive, but rather through the exertions of the organisms themselves. It has been especially through the use and exercise of the various organs in response to the requirements of life, through the increased exercise of physical and mental functions, that the organism has adapted itself more diversely and more fully to the conditions of its life. What one generation acquired in differentiation of structure, in capacities and habits, through its own exertions, it handed on to the next. By c.u.mulative inheritance there ultimately arose the fixed specific characters, and the diversity and progressive gradations of organisms have gone hand in hand with an ever increasing activity. And as with the physical so it has been with the mental. Through continual use and exercise of the functions their capacity has been increased and modified.

Through the frequent repet.i.tion of voluntary actions necessary to life the habitual use of them has come about. Habits that have become fixed are correlated with habitual psychical predispositions. These, gradually handed on by inheritance to the descendants, have resulted in the marvellous instincts of animals. Instinct is inherited habit that has become fixed. Corresponding to this there is on the other hand the recognition-in theory at least-that the disuse of an organ, the non-exercising of a function leads to degeneration of structure and so co-operates in bringing about a gradual but persistent modification of the features and const.i.tution of organisms.

These views, which have grown out of Lamarck's fundamental ideas ("Philosophie zoologique," 1809) are now usually a.s.sociated with the theory advanced chiefly by Etienne Geoffrey St. Hilaire ("Philosophie zoologique," 1830), the opponent of Cuvier, and the ally of Goethe, of the direct influence of the _monde ambiant_. The "surrounding world," the influences of climate, of locality, of the weather, of nutrition, of temperature, of the salinity of the water, of the moisture in the air, and all other conditions of existence, influence the living organism. And they do so not indirectly, as is implied in the process of selection, simply playing the part of a sieve, and not themselves moulding and transforming, but _directly_ by necessitating the production of new developments in the living substance, new chemical and physiological activities, new groupings and changes of form, and new organs.

Darwin himself did not regard these two theories as opposed to the theory of selection, but utilised them as subsidiary interpretations. It is obvious, however, that at bottom they conceal an essentially different fundamental idea, which, if followed out to its logical consequences, reduces the "struggle for existence" to at most a wholly indifferent accessory circ.u.mstance. Weismann felt this, and hence his entirely consistent endeavours to show by great examples, such as the origin of flowers, the mutual adaptations of flowers and insects, the phenomena of mimicry, and many other cases, that neither the Lamarckian nor any other factor in evolution, except only natural, pa.s.sive selection, suffices as an interpretation. From the Darwinian standpoint he is absolutely right, and must needs speak of the "omnipotence of natural selection," for it must either be omnipotent, or it must give place to the other two factors, and retain only the significance we attributed to it in another connection (p. 157), which amounts to saying none at all. It is obvious enough why the discussion as to these factors should centre round the question of the "inheritance of acquired characters," "acquired" either through the use or disuse of organs, the exercise or non-exercise of functions, or through the stimuli of the external world.

The neo-Lamarckian conflict with Darwinism has become more and more acute in recent times, and the neo-Lamarckians have sometimes pa.s.sed from contrasting rival interpretations to excluding the Darwinian factor altogether. As the particular champion of the neo-Lamarckian view, we must name Th. Eimer, the recently deceased Tubingen zoologist. His chief work is in three volumes, ent.i.tled "Die Entstehung der Arten auf Grund von Vererbung erworbener Eigenschaften, nach Gesetzen organischen Wachsens."(43) It is a polemic against Weismannism in all details, even to the theory of "germinal selection." Eimer follows in the footsteps of St.

Hilaire, and shows what a relatively plastic and sensitive creature the organism is to the surrounding world, the conditions of nutrition and other such influences. There is in this connection a particularly instructive chapter on the physiological and other variations brought about by external influences which act as "stimuli of the nervous system."

The whole theory of Lamarck and St. Hilaire transcends-notwithstanding the protests of Eimer to the contrary-the categories of the mechanical theory of life, and this chapter does so in particular. The array of facts here marshalled as to the spontaneous self-adaptation of organisms to their environment-in relation to colour mainly-forms the most thoroughgoing refutation of Darwinism that it is possible to imagine. It is shown, too, by a wealth of examples from osteology, how use (and the necessities of the case-a consideration which again goes beyond the bounds of mere Lamarckism) may modify, increase or diminish vertebrae, ribs, skull and limbs, in short, the whole skeleton.

Ka.s.sowitz is equally keen and convinced in his opposition to natural selection, and in his comprehensive "Allgemeine Biologic"(44) he attacks orthodox Darwinism from the neo-Lamarckian standpoint. The whole of the first volume is almost chapter for chapter a critical a.n.a.lysis, and the polemical element rather outweighs his positive personal contribution. He criticises very severely all attempts to carry the Darwinian principle of explaining adaptations into internal and minute details, arguing against Roux's "Struggle of Parts" and Weismann's "Germinal Selection." And though he himself maintains very decidedly that the ultimate aim of biology is to find a mechanical solution of the problem of life, he criticises the modern hypotheses in this direction without prejudice, and declares them unsuccessful and insufficient, inclining himself towards the "neo-vitalistic reaction" in its most recent expression. Along with Eimer and Ka.s.sowitz, we may name W. Haacke, especially in relation to his views on the acquisition and transmission of functional modifications and his thoroughgoing denial of Darwinism proper. But his work must be dealt with later in a different connection.(45)

These neo-Lamarckian views give us a picture of the evolution of the world that is much more convincing than the strictly Darwinian one. Instead of pa.s.sive and essentially unintelligent "adaptation" through the sieve of selection, we have here direct self-adaptation of organisms to the conditions of their existence, through their own continual restless activity and exertion, an ascent of their own accord to ever greater heights and perfections. A theory of this kind might easily form part of a religious conception of the world. We might think of the world with primitive tendencies and capacities, in which the potentialities of its evolution were implied, and so ordered that it had to struggle by its own exertions to achieve the full realisation of its possibilities, to attain to ever higher-up to the highest-forms of Being. The process of nature would thus be the direct antic.i.p.ation of what occurs in the history of man and of mind. And the task set to the freedom of individual men, and to mankind as a whole, namely, to work out their own nature through their own labour and exertion, and to ascend to perfection-this deepest meaning of all individual and collective existence-would have its exact prelude and preparation in the general nature and evolution of all living creatures.

The transition from these theories of nature to a teleological outlook from the highest and most human point of view is so obvious as to be almost unavoidable. And although a natural science which keeps to its own business and within its own boundaries has certainly no right to make this transition for itself, it has still less right to prevent its being made outside of its limits.

Theory of Definite Variation.