The Fitness of the Environment

as philosophical naturalists exist, be Charles Darwin's greatest title to glory." ^ Recently the work of de Vries, "The Muta- tion Theory," has at length set forth a num- ber of trustworthy observations of the origin of species in plants with which natural selec- tion, in the restricted original sense at least, can have nothing to do. The origin of species by mutation consists in a sudden discontinu- ous variation, and selection, therefore, has no opportunity to operate upon a series of numerous minute variations which them- selves display no tendency of any sort what- ever, in the manner demanded by the Darwin- ian hypothesis.^ Hence it appears certain that natural selection cannot be regarded as completely master of the situation; apart from the origin of life there remains a lacuna in biology which for the present no existing mechanistic hypothesis can fill.

Moreover, among other things, the ordinary processes of regeneration and repair have frequently been brought forward with some success as purposeful activities inexplicable * Du Bois-Reymond, "Darwin »ersMS Galiani," "Reden," Vol. I, p. 211. Quoted from Merz, "History of European Thought in the Nineteenth Century," Vol. II, p. 435. To the same source I am indebted for several other quotations. by natural selection.^ Thus Du Bois-Rey- mond: "One of the greatest difficulties pre- sents itself in physiology in the so-called re- generative power, and — what is allied to it — the natural power of healing ; this may now be seen in the healing of wounds, in the delim- itation and compensation of morbid processes, or, at the farthest end of the series, in the re-formation of an entire fresh-water polyp out of one of the two halves into which it had been divided. This artifice could surely not have been learned by natural selection, and here it appears impossible to avoid the assump-

* "Still less explicable in any way thus far proposed are certain remedial actions seen in animals. An example of them was furnished in §67, where 'false joints' were de- scribed — joints formed at places where the ends of a broken bone, failing to unite, remain movable one upon the other. According to the character of the habitual motions there re- sults a rudely formed hinge-joint or a baU-and-socket joint, either having the various constituent parts — periosteum, fibrous tissue, capsule, ligaments. Now Darwin's hypothesis, contemplating only normal structures, fails to account for this formation of an abnormal structure. Neither can we ascribe this local developnlent to determinants : there were no appropriate ones in the germ-plasm, since no such struc- ture was provided for. Nor does the hypothesis of physi- ological units, as presented in precediog chapters, yield an interpretation. These could have no other tendency than to restore the normal form of the limb, and might be expected to oppose the genesis of these new parts." — Herbeht Spencer, "The Principles of Biology," Vol. I. New York and London, 1909, revised and enlarged edition, p. 362.

tion of formative laws acting for a purpose. They do not become more intelligible by the fact that the regeneration of mutilated crys- tals, observed by Pasteur and others, points to similar processes in inanimate nature. Also the ability of organisms to perfect them- selves by exercise has not found sufficient appreciation with regard to natural selec- tion." 1 To sum up, it appears certain that at least in a few instances, and possibly quite generally, purposeful tendencies exist in the organism which seem to be inexplicable by natural selec- tion or any other existing mechanistic hypoth- esis. It is not too much to hope that a scien- tific explanation of these phenomena in whole or in part may some day be found ; but mean- time they constitute the natural subject of vitalistic speculation. A field remains, though limited, where the physical scientist cannot yet successfully subdue the vitalist, however strong his conviction of the errors of vitalism.^

^ The indeterminism which is based uniquely upon belief in freedom of the will appears to be foreign to the present dis- cussion. It is, accordingly, entirely disregarded in the follow- ing considerations. Hence the conclusions of the present in- quiry are not to be taken as cognate with such metaphysical hypotheses as the indeterminism of Kant and Lotze. Vitalism therefore flourishes, as the recent remarkable works of Driesch and Bergson tes- tify. Of these two authors the former is concerned to prove that pure mechanism is insufficient in biology, and that to mechanism must be added his entelechies ; ^ the latter has gone beyond the vitalism of earlier au- thors, to give his own view of his speculations, and introduced the idea of the vital impetus.

Upon analysis the theory of Bergson amounts to this, that there is an original creative impetus impelled upon life which, at all events in the main, is responsible for the course that organic evolution has taken. To quote his own words: "So we come back, by a somewhat roundabout way, to the idea we started from, that of an original impetus of life, passing from one generation of germs to the following generation of germs through the developed organisms which bridge the interval between the generations. This im- petus, sustained right along the lines of evo- lution among which it gets divided, is the fundamental cause of variations, at least

1 Driesch, "The Science and Philosophy of the Organism." London, 1907 and 1908, two volumes. of those that are regularly passed on, that accumulate and create new species. In gen- eral, when species have begun to diverge from a common stock, they accentuate their diver- gence as they progress in their evolution. Yet, in certain definite points, they may evolve identically ; in fact, they must do so if the hypothesis of a common impetus be accepted. This is just what we shall have to show now in a more precise way, by the same example we have chosen, the formation of the eye in molluscs and vetebrates. The idea of an 'original impetus,' moreover, will thus be made clearer." ^ . . . "If life realizes a plan, it ought to manifest a greater harmony the further it advances, just as the house shows better and better the idea of the archi- tect as stone is set upon stone. If, on the contrary, the unity of life is to be found solely in the impetus that pushes it along the road of time, the harmony is not in front, but behinc The unity is derived from a vis a tergo: il is given at the start as an impulsion, not placed at the end as an attraction. In com- municating itself, the impetus splits up more and more. Life, in proportion to its progress, is scattered in manifestations which un-

doubtedly owe to their common origin the fact that they are complementary to each other in certain aspects, but which are none the less mutually incompatible and antagonistic." ^ The contention of Bergson may be divided into two parts : a statement of belief in an original impetus, and his biological argu- ments in favor of such a view. The former, in so far as it is a question exclusively of an original impetus, appears to lie outside the scope of science, in company with speculations upon the origin of the universe; the latter, because it deals with the subject-matter of science, is open to scientific criticism, and from the standpoint of the biologist is certainly far from conclusive.^

Bergson's hypothesis is, however, in es- sence not less vitalistic than that of Driesch. Both philosophers assume the existence of a special vital characteristic, and explain the course which evolution has taken as a result of it. In short, modern vitalism consists in postulating a directive tendency which manifests itself in or through the organism alone, and is peculiar to life. ' In fact, until the mechanistic operation of Bergson's impetus can be clearly perceived, it must remain scientifically an unsound hypothesis.

In such speculations the properties of matter and the process of cosmic evolution have no place.^ Bergson, indeed, very defi- nitely, and it would seem gratuitously, puts aside cosmic evolution and also, with certain slight reservations, the properties of matter as of no essential consequence in organic evolu- tion; e.g. "This twofold result has been ob- tained in a particular way on our planet. But it might have been obtained by entirely dif- ferent means. It was not necessary that life should fix its choice mainly upon the carbon of carbonic acid. What was essential for it was to store solar energy ; but, instead of ask- ing the sun to separate, for instance, atoms of oxygen and carbon, it might (theoretically at least, and, apart from practical difficulties

^ Driesch, to be sure, has considered the problem of uni- versal teleology, but unsuccessfully and with obvious vitalistic preconceptions such as individuality. His nearest approach to the thesis of the present work is to be found in the follow- ing lines : "I do not hesitate to confess that, apart from historical teleology relating to the sequence of one state of poli- tics or economy upon another, and apart from phylogeny, there seems to me to be a certain sound foundation in the concept of the general harmony between organic and inor- ganic nature, a something which seems to show that nature is nature for a certain purpose. But I confess at the same time that I am absolutely unable to consider this purpose in any other than a purely anthropomorphic manner." — L.c, Vol. n, pp. 348-349.

possibly insurmountable) have put forth other chemical elements, which would then have had to be associated or dissociated by entirely dif- ferent physical means. And if the element characteristic of the substances that supply energy to the organism had been other than carbon, the element characteristic of the plastic substances would probably have been other than nitrogen, and the chemistry of living bodies would then have been radically different from what it is. The result would have been living forms without any analogy to those we know, whose anatomy would have been different, whose physiology also would have been different. Alone, the sensori-motor function would have been preserved, if not its mechanism, at least in its effects. It is there- fore probable that life goes on in other planets, in oilier solar systems also, under forms of which we have no idea, in physical conditions to which it seems to us, from the point of view of our physiology, to be absolutely op- posed. If its essential aim is to catch up usable energy in order to expend it in explo- sive actions, it probably chooses, in each solar system and on each planet, as it does on the earth, the fittest means to get this result in the circumstances with which it is confronted. That is at least what reasoning

by analogy leads to, and we use analogy the wrong way when we declare life to be impos- sible wherever the circumstances with which it is confronted are other than those on the earth. The truth is that life is possible wher- ever energy descends the incline indicated by Carnot's law and where a cause of inverse direction can retard the descent — that is to say, probably, in all the worlds suspended from all the stars. We go further : it is not even necessary that life should be concen- trated and determined in organisms properly so called, that is, in definite bodies present- ing to the flow of energy ready-made though elastic canals. It can be conceived (although it can hardly be imagined) that energy might be saved up, and then expended on varying lines running across a matter not yet solidified. Every essential of life would still be there, since there would still be slow accumulation of energy and sudden release." ^

These conclusions appear to be based upon decisions regarding the essential physico-chem- ical conditions and characteristics of life arbi- trarily reached in accordance with precon- ceived views, and quite without scientific justification. There is certainly no reason to ascribe greater importance to energy than to matter in the vital processes, and in the light of the facts with which the preceding chapters are concerned, such views seem absurd. Indeed, whoever is disposed to spec- ulate about biological fitness — and not even the incomparable finesse of M. Bergson's dia- lectic can make fitness other than the most general result of the process of organic evolu- tion — must now weigh well the cosmic pro- cesses. For, if allowance be made for the results of natural selection in the organic world, fitness of the environment has the greater claim to be considered.

The two fitnesses are complementary; are they then single or dual in origin ? The simple view would be to imagine one common impe- tus operating upon all matter, inorganic and organic, through all stages of its evolution, in all its states and forms, and leading to worlds like our own through paths apparently purposeful and really not yet explained. Such, it seems to me, is the natural hypothesis for the vitalist to adopt. But then vitalism vanishes, only teleology remains; for the unique characteristic of life is gone. Yet,

putting aside mechanistic differences, is it not now lost in any case ? Has not modern vital- ism in accepting the limitation to entelechies or impetus destroyed itself ? The situation, briefly, seems to be as fol- lows : two evolutionary processes independ- ently result in two complementary fitnesses; hence they are related. In the one process the origin of fitness is in part explained by a mechanistic hypothesis. Nevertheless, many philosophers, as is their right, declare that in this process a further extraphysical influence is to be assumed. But any one who makes such an assumption for the one process must certainly now make it for the other ; thus he will be led to see impetus or entelechies every- where. Under these circumstances it may be doubted if his acquaintance with the na- ture of his impetus or entelechies is so inti- mate that he will be able to distinguish the inorganic from the organic, for he has surren- dered to science all the positive physico-chem- ical differences between organic and inorganic bodies and processes. Hence, unless he is to make an arbitrary and unintelligible distinc- tion, or to indulge in the spinning of cob- webs, his vitalism has ceased to be exclusively organic, in short has ceased to be vitalism at all, and has become mere universal teleology.

But, for the scientist, these are matters of little moment. He, at least, is not obliged to take any stand concerning them. This could hardly be better illustrated than by our new facts themselves. For it seems to be clear that where science is most self-sufficient, at the very basis of physical science itself, if anywhere, teleology is at work. Yet it is certain that physical science needs no tele- ology to explain its phenomena and pro- cesses. These are mechanisms, and since the publication of Newton's "Principia" no one has seriously doubted the fact.^

To-day there is as little room for doubt that a complete description of cosmic evolution in terms of matter and energy is possible; for it is sound scientific doctrine that wh9,t exists in the finished solar system depends upon what already existed in the nebula. The forms and states and quantities of matter and energy in the nebula determine the re- sulting solar system. Further, since both nebulae and solar systems are common oc- * Laplace's reply to a question of Napoleon's, "Why the name of God did not occur in his ' Mecanique celeste,' " will be recalled : "Sire, je n'ai pas besoin de cet hypothese."

currences, it is evident that nebulae them- selves are in a general way determined by other antecedent conditions and phenomena, which turn out to be collisions between stars. Thus arises the suspicion that cosmic evolu- tion may be in truth a cyclic process which had no beginning and can have no end.^ An alternative hypothesis regards the pres- ' Such a view, until quite recently, was universally rejected bscause it appeared to conflict with the second law of thermo- dynamics, — that of the degradation of energy. But lately it has been put forth by no less an authority than Arrhenius, who has advanced a theory to explain away the difficulty of the second law.

"The recognition of the indestructibility of energy seemed to accentuate the difficulties of the cosmogonic prob- lems. The theses of Mayer and of Helmholtz, on the man- ner in which the Sun replenished its losses of heat, have had to be abandoned. My explanation is based upon chemical reactions in the interior of the Sun in accordance with the second law of thermodynamics. The theory of the 'degra- dation' of energy appeared to introduce a still greater diffi- culty. That theory seems to lead to the inevitable conclu- sion that the Universe is tending towards the state which Clausius has designated as 'Warme Tod' (heat death), when all the energy of the Universe will be uniformly distributed through space in the shape of movements of the smallest particles. That would imply an absolutely inconceivable end of the development of the Universe. The way out of this difficulty which I propose comes to this: the energy is 'de- graded ' in bodies which are in the solar state, and the energy is 'elevated,' raised to a higher level, in bodies which are in the nebular state." — Arrhenius, "Worlds in the Making," translated by Boms. New York and London, 1908, p. xiii.

ent form of our universe as the result of a gradual evolution from an earlier unknown form, the development of successive solar systems being mere incidents of the larger process, the evolution as a whole directively governed by the law of the degradation of energy. In either hypothesis the remarkable sys- tematic relationship between the elements which is manifest in the periodic classifica- tion has a peculiar place. If the second hy- pothesis be accepted, there seems to be little room for doubt that at an early period the chief cosmic process was the evolution of the elements themselves; and in the first theory the nebula, whose properties depend almost wholly upon chemical constitution and chem- ical and molecular energy, occupies a unique position, like the leaf in the organic cycle, or spring among the seasons. Thus, whether or not the periodic system is to be regarded as the one remaining plain result of a process by which the elements were evolved, at least it takes precedence over the other properties of matter, and lies at the very foundation of the known processes of evolution. Clearly,

no one can doubt that upon the properties of matter as determined by the periodic system, and upon the relative amounts of the different elements, the actual process of cos- mic evolution from nebula to solar system is dependent.^ Hence, in accordance with the general method of science, we must assume that the origin of environmental fitness lies at least as far back as the phenomena of the periodic system, at least as far back as the evolution of the elements, if they were ever evolved. We simply cannot doubt that the origin of a body like the earth depends exclusively upon chance plus the properties of the elements, their relative amounts, the indestructible forces of nature, and the other known factors of mechanism. The perfect induction of phys- ical science, based upon each and all of its countless successes in every department of physics and chemistry, conclusively proves that the whole process of cosmic evolution from its earliest conceivable state to the pres- ent is pure mechanism.^

^ The same considerations apply to any other scientific hypothesis of the genesis of the solar system. " Not only is this proved by all experience of physical science, it has also ever been the necessary working hypoth- esis of physicists and chemists. If, then, cosmic evolution be pure median- ism and yet issue in fitness, why not organic evolution as well ? Mechanism is enough in physical science, which no less than biolog- ical science appears to manifest teleology; it must therefore suffice in biology.

Thus once more we arrive at the negation of vitalism. For this conclusion we possess two arguments: the argument that in such aspects as concern physical science, and apart from diflEerences scientifically explicable, or- ganic and inorganic phenomena are alike, and therefore a specifically vital teleology is un- necessary; and the argument that inorganic science unquestionably has no need of non- mechanistic teleology. Hence we are obliged to conclude that all metaphysical teleology is to be banished from the whole domain of natural science.^

What then becomes of fitness .'' Clearly there are two logical possibilities. Either there exists an unknown mechanistic explanation of that common issue of the organic and cosmic 1 Such at least is the simplest provisional hypothesis, and the only view which involves no gratuitous assumptions. It is therefore the one which must now be adopted. evolutionary processes, or there does not. If such an explanation be possible, at least it must be admitted that it is very hard to con- ceive. Yet, recalling the diflSculty before the idea of natural selection arose of imagining any mechanistic explanation whatever of fitness, we shall do well not to decide against such a possibility.

On the other hand, it is conceivable that a tendency could work parallel with mechanism without interfering with it, according to a view which has been held by such thorough- going mechanists as Descartes, Claude Ber- nard, Virchow, DuBois-Reymond, and many another. Although I have no intention of here seeking a choice between these two hy- potheses, being in fact convinced that now, at all events, no choice is scientifically possi- ble, and doubting if properly speaking they are alternatives at all,^ I do feel concerned to

^ "Either the multitudmous kinds of organisms which now exist, and the far more multitudinous kinds which have existed during past geologic eras have been from time to time sep- arately made, or they have arisen by insensible steps, through actions such as we see habitually going on. Both hypotheses imply a Cause. The last, certainly as much as the first, recognizes this Cause as inscrutable. The point at issue is, how this inscrutable Cause has worked in the production of living forms. This point, if it is to be decided at all, is to be decided only by examination of evidence. Let us inquire which of these antagonistic hypotheses is most congruous

remove from the latter view, if I may, some of the objections which are commonly raised against it in scientific circles, conscious that in this attempt I am overstepping the bound- aries of natural science. It is evident that a perfect mechanistic description of the building of a house may be conceived. Within the world of physical science the whole process is logically complete without consideration of the architect's de- sign and purpose. Yet such design and purpose, whether or ' not in themselves of mechanistic origin, are at one and the same time determining factors in the result, and nowise components of the physical process. Now it seems clear that a similar effect of a tendency working steadily through the whole process of evolution is also at least conceive- able, however small its bearing upon science, provided, like time itself, it be a perfectly independent variable, making up, therefore, with time the constant environment, so to speak, of the evolutionary process. The tend- ency must not be demonstrable either by weighing or by measuring, else it would amount to an interference within the mech-

with established facts." — Hekbebt Spenceb, "The Prin- ciples of Biology." New York and London, 1909, Vol. I, revised and enlarged edition, p. 416. anistic process, and it must not be itself liable to any kind of variation whose detec- tion would directly reveal it. Where then can the origin of such a tendency be located? Why clearly, if we accept the induction in favor of mechanism, only where Bergson has shrewdly placed his vital impetus, at the very , origin of things, just before mechanism begins to act. In short, our new teleology cannot have originated in or through mechanism, but it is a necessary and preestablished asso- ciate of mechanism. Matter and energy have an original property, assuredly not by chance, which organizes the universe in space and time.

This is in very truth a metaphysical doc- trine; but it has strong claims to sympa- thetic regard from men of science. In the first place, it leaves mechanism with the perfectly free hand which that process has undoubtedly earned in the world of phe- nomena. Secondly, it does but add one further riddle, and that an old and familiar one, to those two already tacitly recognized by most scientists : the existence of the universe and the existence of life. Given the universe, life, and the tendency, mechanism is inductively proved sufficient to account for all phenomena. The existence of the universe, on the other