product, fundamentally, of natural forces constrained along lines of development imposed by external conditions, no matter whence derived, and capable of transmitting whatever it possesses, however acquired. It would seem that it should be apparent, we insist, that it is the existing form, however acquired, that must be transmitted, actually or potentially, to render possible the protean changes which organisms exhibit. Briefly, Darwin's theory of organic evolution, aside from its features of artificial and sexual selection, as is clearly to be seen by any one who carefully reads his works, and, as is admirably set forth by Herbert Spencer in his "Factors of Organic Evolution," recognizes that the power of both natural and artificial selection to accumulate variations would be neutralized, unless use and disuse of parts by organisms so changing did not continuously tend to mold them, functionally and structurally, as associated with environment, in directions conformable to the primary change.

He who accepts Darwin's theory of evolution, which involves recognition of the strictest heredity through all the changes wrought by natural selection, should logically also accept hereditability for characters otherwise acquired. He sees, as the effect of stress in purely natural environment, all change handed down to posterity, and everywhere discarded forms dwindled to rudiments in the adult animal, or lying latent in the embryo, and he has no logical right to regard change beyond the apparent limits of stress in natural environment as beyond the pale of transmission to posterity. The demonstrable, systemic change in natural environment is the cogent underlying ground for belief that all change, regardless of the fact that an environment may not be purely natural, is transmitted, at least potentially, even if it escape our demonstration in the individual case as existing. This is the à priori deduction from acceptance of the theory of natural selection as true, but it is, à posteriori, supported by numerous facts that do not seem to reach the

apprehension of the opponents of this view. This state of mind is well described by Herbert Spencer, when, in speaking of the dawn of discussion as to organic evolution, he said, "I look back with surprise at the way in which the facts which were congruous with the espoused view monopolized consciousness and kept out the facts which were incongruous with it-conspicuous though many of them were."

Considering that man is the summit of nature as we know it on earth, in whom nature is completed and crowned, and that the effects of his agency are, therefore, a part of nature; considering, too, that nature's deviations upon its sole responsibility are not always explicable; considering all the facts we know, it seems blind to limit the power of evolution to lines beyond which we may well ask, If it be not Nature there working, what is working there? Yet it is denied, by such persons as we have described, that characters are acquired except through natural selection. They explicitly rule out as transmissible not only characters arising from physiological, but also those arising from pathological, change of function; that is, they dispute the existence of the hereditability of acquired characters, whether in health or disease.

Let us, for the sake of obtaining a broader view of the general subject under discussion, note in passing the difference between the two existing doctrines of evolution. One side holds that incorporate with the organism itself is the principle of its life and growth, largely independent of environment. That is to say, according to this view, environment represents only an auxiliary principle in development. This view, it ought to be seen at a glance, is untenable in face of the large adaptedness of living things at a given instant of time to their environment. So close is this relation of living things to their surroundings that unscientific persons still regard them as having been created from the beginning just as they now exist.

The other side to this controversy-which side, with whatever modifications, includes the mass of scientific men-is with Darwin. It grants that the organism is, in fact, endowed with a vital principle involving determinate tendencies as to size, form, and habitat, but affirms that it is, through the character of its environment, modified so as to be in accord with change in the environment, or else is extirpated. In other words, it is alleged by this side that the vital principle and law of growth in an organism represent forces which encounter in the organism other forces represented by the environment, and that, as the organism must in consequence either live or die, or have well or ill being, according to the suitableness or unsuitableness of its environment, or its final ability or inability to conform to its environment, the character of its existence at any given point of time is the resultant of those forces, plus the concomitant force of conformability in function and structure to the primary change through the use and disuse of vital parts of the organism. According to this theory, in which we have implicit faith, the principle with which the organism is endowed renders it, with time, more or less adapted to its changed environment, individuals incapable of variation dying off, and, if without sufficient time, all paying the penalty of death from inability to meet the new demand upon their vitality.

That the effects of use and disuse of vital parts are, in fact, if not clearly, implied by the doctrine of the survival of the fittest in the struggle for existence, ought to be seen when we consider that, in the change of species through the ages, nature could have given nothing directly out of hand, but only indirectly, as by parcels, through the medium of both environment and habit acting on the organism. A variety issuing out of the loins, so to speak, of its predecessors, to be perhaps finally represented by a species very unlike them, is subjected by nature to what, to enable it to change? Fundamentally to changed

exterior physical conditions. But the coincident effect to which it is subjected, inseparable from those new conditions, is the tendency to the use and disuse of vital parts. The tendency in this case means the actual use and disuse, however at first feeble, of those vital parts of the organism. Use and disuse of such parts could be the only efficient cause, relatively speaking, of securing stability of the primary modifications from natural selection. Given variability, which is admitted, and variation, which must be if variability is, and we find that use and disuse of vital parts, internal as well as external, must accompany and confirm primary change, or else it would prove abortive. How otherwise can we understand that, in the course of ages, structures have changed so as, without scrutiny of many intermediate forms, to render animals hardly recognizable as the descendants of their demonstrated ancestors, when at the same time we recognize them as so well adapted to their present environment, and the old form as less adapted to it, or not at all?

Hence we, for our part, contend that change of function is inseparable from change of structure, that they are so intimately linked in the bond of life that they change pari passu, and that discussing them separately should be regarded only as a matter of convenience. Hence, we believe in the transmission of all characters, however acquired, for there is, à priori, no reason for excluding the germinative plasm of organisms from the somatic or bodily plasm of organisms, and, à posteriori, no reason for so doing in the face of a multitude of confirmatory facts.

In the affection of the germinative plasm of the organism, coincidently with the outward change of the organism, through change of environment and all that that implies in changed habits and food, and through use and disuse of vital parts and consequent change in function and structure, all the effects shown in the adaptation of the organism, through its reaction to its environment, are summed up. Unless this be the process

of organic development it is subject to no law but that which makes it the false seeming of a reality. Therefore, as law is apparently omnipresent we can afford to say that, unless it be a real law that we seem to see, there is no organic evolution; but, on the contrary, if that seeming be real, that the law involves the transmission of all characters, those arising from the intervention of man, those termed fortuitous, as well as those arising in the stress of the most implacable struggle for existence, and consequently in all these blended.

The reader is now better prepared to consider understandingly the statements which, we said at the beginning, had awakened our surprise. We will treat of them seriatim, with somewhat more amplification than as there recorded.

If,

The first learned gentleman attempted to show that, the vital principle apart, all organic changes are, within the environment, chiefly consequent upon the use and disuse of vital parts. This is not, as we have intimated, a correct view. The use and disuse of vital parts is a vera causa, but not the primary one. The primary one, in order of importance and time, is the action of nature, exclusive or inclusive of man, in producing the variation which other agencies, even artificial and sexual selection in the higher organisms, subsequently contribute to mold. in the stress which nature puts upon organic life, disuse did not follow diminished usefulness, and increased usefulness greater use, and structure in conformity to both, change could not be permanent, for variation in any part necessitates functional and structural change in all, especially in co-ordinate parts. Whatever Darwin might have said, the effect of use and disuse of parts must lie back of his theory of organic evolution as the indispensable cause of permanent change; not of mere change, let the reader mark, but of permanent change in determinate directions. Darwin, however, affirms the fact in some places in his works and implies it in others. In the following passage he