Darwin's theory is condemned by its advocates. For it is one of a class of theories which, they contend, are not entitled to any consideration or hearing in a scientific court of inquiry. Doubtless many of our readers, at least those conversant with science, have spent many a pleasant hour perusing numerous well-written pages filled with protests against the ascription of phenomena to such entities as "plastic force," "vital power," "intrinsic aptitude," "inherent tendency," etc. This attribution is one of the stock objections against every thing which does not tally with the ideas current among positivists. The advocates of Darwin, of whom most, if not all, are followers of Comte, wax eloquent and enthusiastic while on this theme. Here they disport themselves after the manner of men conscious of having alighted on a subject highly calculated to call forth their most happy thoughts. Here their rhetoric is consummate, and their turns of expression singularly felicitous. Their affected indignation at the assumed absurdity of thus accounting for phenomena knows no bounds. So thrilling is this tirade, and so perfect the simulation of honest indignation, that we, though of a somewhat cold temperament, have, through sympathy, often caught and retained for a moment the infection of enthusiasm. When our feelings ceased to have full sway, and when our reason returned, we were in a fit state to appreciate fully the great power of eloquence.
After animadverting thus severely on this ascription of phenomena, it was not to be expected that these positivists would be guilty of the inconsistency of advocating a theory the basis of which was one of these "metaphysical entities." Very little credence, we are sure, would be given to the assertion that the foundation of Darwin's theory was an occult quality. For that theory has again and again been held up to the world as a shining sample of what can be effected in science by conformity to the positive process of discovery. Yet such is the case. Darwin, on page 2, Vol. I. of his late work, says, "If organic beings had not possessed an inherent tendency to vary, man could have done nothing." In numerous other portions of his work may be found the reference of variations to "an innate spontaneous tendency," (p. 362, Vol. I.,) to "spontaneous or accidental variability," (p. 248. Vol. II.,) to the "nature or constitution of the being which varies," (p. 289, Vol. II.,) and to "other metaphysical entities." So frequent is the recurrence of these expressions that it is scarcely possible to open any portion of his work and not alight on one. The whole of Darwin's theory is deduced from this occult quality in animals and plants. And this is a theory advocated by G. H. Lewes, and a number of others who have given in their adhesion to positivism! If this explanation is, as they claim, unphilosophical, are they not bound to withdraw their support from such a theory? Does not their present position argue a total want of consistency? Which is the more entitled to support, even from their own professed stand-point, a theory which refers favorable variations to an innate tendency in organisms, or that which ascribes variations to reversion? No; as any other view would be incompatible with the success of their darling theory, they are perfectly content to consider variation as an ultimate law, even though such a consideration involves a gross inconsistency. Regardless of this, they advance the theory, and, when engaged on a collateral point, marvel at their opponents for doing that which they have done at the start, and complacently extol the clearness of their own views, which have been arrived at by the aid of an hypothesis based upon the same occult quality against which they are now exhausting all their eloquence.
The truth is, that these "metaphysical entities" are in almost as frequent use among positivists as among their adversaries. They are, perhaps, more ingeniously disguised. But a close examination of their speculations will elicit the fact that they are guilty of the same (alleged) absurdity, and on a point, as in the present instance, most materially affecting their whole theory. But these explanations are denounced as metaphysical merely to facilitate the reception of their finely spun theories. The dawn of science in any department of knowledge is invariably preceded by a mist. This acts as a false medium, through which the subjects of science are dimly seen, presenting a most monstrous aspect. This is rendered still more distorted by the ingenious but absurd theories of men bent upon tracing a want of harmony between science and religion. Their hypotheses, at first sight, apparently preclude the need of these phrases, but they are at last necessitated to use them in accounting for phenomena of which the ascription to known factors would be grossly at variance with their views. The use of these entities is in some cases only provisional with us, to be abandoned on the advent of true knowledge; for religion does not shun the light of true science. In this transitional period between complete ignorance and full knowledge, these speculative theories are propounded. They purport to furnish an explanation of all phenomena, and to dispense with the necessity of using "metaphysical entities." Their adoption is necessitated, contend their propounders, if the converse theories are conceded to be unscientific. This we deny, and appeal to the existing low condition of scientific knowledge, which precludes for a time the possibility of the formation of any well-founded theory. This theory of evolution, for instance, is confessedly founded on ignorance—ignorance of the law to which its data conform. But when science advances, and when facts are exposed to the clear sunlight of precise and impartial investigation, perfect harmony is observable between science and religion; and the absurdity of the theories which were urged for our adoption becomes manifest. Past experience justifies our belief that such will ever be the case. For it is only those departments of knowledge which are abandoned to speculation which present facts seemingly at variance with religion. We refuse to accept the alternatives which they offer, confident that, as they are at variance with religion, they are not the legitimate products of true science.
Races under nature have been formed exclusively by degeneration. By this we do not wish to imply any innate tendency in organisms to degenerate. The degeneration of which we speak is solely induced by the direct and indirect action of the conditions of life. Upon assuming certain conditions necessary to full growth, the formation of natural races becomes deductively explicable. It is with regret that we observe a disposition on the part of some of the advocates of special creation to believe growth independent of the conditions. The dependence of growth upon the conditions cannot be disputed. Nor do we wish to dispute it; for it is, to our mind, strong confirmation of the doctrine of final causes. The supporters of the evolution hypothesis maintain that an organism has the capacity for adapting itself to any conditions, so that they are not so marked and sudden as to entail extinction. We acquiesce in this thus far—where the conditions are favorable, improvement ensues. But with us improvement implies previous degeneration. And when the conditions are adverse, a change for the worse results in proportion to the change in the conditions. Such adaptation as this we admit. But we fancy Darwin would consider this too teleological to be a concession. Adaptation, with him, implies harmony. This harmony we will not gainsay. But if the conditions induce the total or partial suppression of any part or character, we contend that this adaptation of the organism to the conditions is not consistent with complete physiological integrity. The departure from a state of integrity is directly proportioned to the retardation of growth of either the organism as a whole, or of only one or more of its organs or characters. This repression is the criterion by which to judge of the adverseness of the conditions. For our belief in this incompatibility between full integrity and conditions which entail the loss or diminution of any part, character, feature, or organ, we will, in a future article, furnish full warrant.
Starting out, then, with perfect specific types, we will be able to account for the formation of races without the aid of an equivocal process, without postulating any occult quality, and by means in every way analogous to those which, as Darwin has shown, play an important part in inducing modification.
From the instances of degeneration adduced by Darwin, we may infer that the conditions of life were at one time extremely adverse. And surely, if they were sufficiently unfavorable to involve the reduction of most important organs to a rudimentary condition, they must also have caused the suppression of many minor characters. The climate in most countries has been adequately rigorous to act upon the organization as a whole, and thus entail deterioration in size; and as these unfavorable conditions ranged from those but little unfavorable to those barely compatible with life, the retention of the organism in each or several of these stages would create diversity of size; for climate acts with different degrees of force in different countries. Then in a single country the animals or plants would be subjected to closely similar conditions, and long continued subjection to these would produce uniformity of size, and indigenous races.
In addition to these modifications consequent upon the direct action of the climate on the whole organization, there would result minor changes. The conditions of life would in different districts or countries be unfavorable to different parts or characters. The reduction of these parts would follow, and this would, through correlation of growth, involve modifications in other portions of the organization. For, says Darwin, "all the parts of the organization are to a certain extent connected or correlated together."
Owing to these causes there would be disproportionate deterioration of the characters. When an organ of which the function is activity would be little exercised, it would become atrophied. Different situations would occasion more or less disuse of organs, and these would consequently be differently modified. Then their modification would call for the modification of other characters. Thus, the legs in some animals are made more or less short by disuse, and by correlation the head is reduced in size, and changed in shape. Loss of characters, such as the crest of feathers on the head, and wattle, conjoined with changes in other parts of the organism, would, through correlation, produce more or less diminution in size of the skull. General decrease in size, and loss of tail or tail-feathers, would lessen the number of the vertebræ, which result would induce other changes. When the hair is affected by humidity of climate or other causes, the tusks, horns, skull, and feet become modified. There is also correlation of degeneration between the skin and its various appendages of hair, feathers, hoofs, horns, and teeth; between wing-feathers and tail-feathers; between the various features of head and skull.
With animals, a small supply of food would cause decrease in size; and with plants, an insufficient quantity of the necessary chemical elements, together with the starvation consequent upon the close contiguity of other plants, would produce the same result. Diseases peculiar to certain localities, heights, and climates have also played their part in the modification of animals and plants.
Given, then, a perfect type, the unfavorable action of these elements—heat and cold, dampness and dryness, light and electricity, disuse, disease, absence of some of the necessary chemical elements, and insufficient supplies of food—together with that of their countless modifications, acting separately and conjointly, directly and indirectly through correlation, is amply adequate to the production of the modifications by which, as we conceive, races have been formed.