Although Mr. Darwin has insisted so strongly on the similarity between our bodily structure and that of the lower animals, and although he has endeavored to convince us that the human ovule differs in no respect from the ovules of other animals, yet he is compelled by abundant evidence to admit that there is something in man which does not exist in the lower animals, and something in the lower animals which does not exist in man. How does he account for these organic differences? Men of science, only twenty years ago, would have explained the fact by the old philosophical and scientific axiom, Omne animal generat simile sibi, which means that each species of animals has progenitors of the same species; whence they would have inferred by legitimate deduction that animals of different species owe their specific differences to their having issued from progenitors of different species. This explanation was universally received, as it was supported by an induction based on centuries of observation, without a single example to the contrary. It was, therefore, a truly scientific explanation. But twenty years are passed, and with them (if we believe Mr. Darwin) the axioms, the logic, and the experimental knowledge of all centuries have disappeared from the world of science, to make room for higher and deeper conceptions. It was not an easy task, that of giving the lie to a uniform and perpetual experience; but to Mr. Darwin nothing is difficult. He needs only a word. With one word, “Rudiments,” he is confident that he will transform the objections of the old science into arguments in his favor, just as King Midas by the touch of his hand transmuted everything into shining gold.
The world has hitherto believed that man has only two hands, whereas the monkey has four. But we must not say this in Mr. Darwin’s face. If we did, he would inform us that we are strangely mistaken. Man, he pretends, belongs to the order of quadrumana; hence he has four hands no less than the monkey, though two of them are used as feet, which may be considered as rudimentary or undeveloped hands. If we were to remark in his presence that monkeys have a tail, whilst man can boast of no such elegant appendage, he would immediately confound our ignorance by informing us that we all possess a rudimentary tail, which might be made to develop and grow by mere local irritation.
In this way he explains all the organic differences which separate one species from another. Every difference is made to depend either on the development in man of an organ which is undeveloped and rudimentary in lower animals, or on the development in lower animals of some organ which is rudimentary and undeveloped in man. To explain this theory he reasons as follows:
“The chief agents in causing organs to become rudimentary seem to have been disuse at that period of life when the organ is chiefly used (and this is generally during maturity), and also inheritance at a corresponding period of life. The term ‘disuse’ does not relate merely to the lessened action of muscles, but includes a diminished flow of blood to a part or organ from being subjected to fewer alterations of pressure, or from becoming in any way less habitually active. Rudiments, however, may occur in one sex of those parts which are normally present in the other sex; and such rudiments, as we shall hereafter see, have often originated in a way distinct from those here referred to. In some cases organs have been reduced by means of natural selection, from having become injurious to the species under changed habits of life. The process of reduction is probably often aided through the two principles of compensation and economy of growth; but the later stages of reduction, after disuse has done all that can fairly be attributed to it, and when the saving to be effected by the economy of growth would be very small, are difficult to understand. The final and complete suppression of a part already useless and much reduced in size, in which case neither compensation nor economy can come into play, is perhaps intelligible by the aid of the hypothesis of pangenesis.”
On this passage, which forms the main foundation of the Darwinian theory of rudiments, much might be said; but we must limit ourselves to the following obvious remark. Science and philosophy reason on ascertained facts, but do not invent them; whereas Mr. Darwin in this very passage, as in many others, not only invents with poetic liberty all the facts which he needs to build up his theory, but also violates the laws of reasoning by drawing from his imaginary facts such conclusions as even real facts would not warrant. Philosophy would certainly not allow him to assume without proof that “organs become rudimentary”; for this is not an ascertained fact. Nor would philosophy permit the gratuitous introduction of rudiments derived “from the corresponding organs of other more developed animals”; for there is no evidence that such has ever been the case. Nor would philosophy sanction “the final and complete suppression of a part already useless”; for on the one hand we have no means of knowing whether a part be really useless, and on the other no total suppression of organic parts has ever been known to occur (except in monsters) within the range of any given species. Nor would philosophy permit an appeal to the hypothesis of pangenesis or to the principle of compensation to evade the difficulties of which the new theory cannot give a solution; for the hypothesis of pangenesis is itself in need of proof, and the principle of compensation involves, in our case, a begging of the question, inasmuch as it assumes the mutability of species—the very thing which the theory is intended to demonstrate.
But, says Mr. Darwin, perhaps the hypothesis of pangenesis would make “intelligible” the suppression of a useless part. Let it be so, though we hold the contrary to be true; what then? Is all hypothesis to be accepted which would make a thing “intelligible”? The succession of days and nights was intelligible in the Ptolemaic hypothesis; the loss of a battle becomes intelligible by the hypothesis of treason; the death of an old woman is intelligible by the hypothesis of starvation; but no man of sense would mistake the hypothesis for a fact. The truth is that Mr. Darwin, before attempting the explanation of what he calls “the final and complete suppression of a part,” was bound to prove that the absence of such a part was a real suppression of the pre-existing part. This he has not done; in fact, he had no means of doing it. Hence all his reasonings on this subject are paralogistic, and his theory of rudiments is a rope of sand.
The preceding remarks are fully applicable to the other examples of rudiments given by the author in the fourteen remaining pages of the chapter. Thus, “rudiments of various muscles have been observed in many parts of the human body.” We flatly deny the assertion. “Not a few muscles which are regularly present in some of the lower animals can occasionally be detected in man in a greatly-reduced condition.” We answer that such muscles are not at all in a reduced condition, but in the condition originally required by the nature of the individual. “Remnants of the panniculus carnosus in an efficient state are found in various parts of our bodies; for instance, the muscle on the forehead by which the eyebrows are raised.” On what ground can this muscle be called a remnant? “The muscles which serve to move the external ear are in a rudimentary condition in man.... The whole external shell (of the ear) may be considered a rudiment, together with the various folds and prominences which in the lower animals strengthen and support the ear when erect.” Where is the proof of such rudimentary condition? “The nictitating membrane is especially well developed in birds, ... but in man it exists as a mere rudiment, called the semilunar fold.” How is it proved that the semilunar fold is a mere rudiment, and not a special organism, purposely contrived by the hand of the Creator at the first production of man?
Mr. Darwin goes on making any number of assertions of the same kind, not one of which is or can be substantiated, and yet at the end of the chapter closes his argumentation in the following triumphant words:
“Consequently, we ought frankly to admit their community of descent [of man and other vertebrate animals]. To take any other view is to admit that our own structure, and that of all the animals around us, is a mere snare laid to entrap our judgment. This conclusion is greatly strengthened, if we look to the members of the whole animal series, and consider the evidence derived from their affinities or classification, their geographical distribution and geological succession. It is only our natural prejudice, and that arrogance which made our forefathers declare that they were descended from demi-gods, which leads us to demur to this conclusion. But the time will before long come when it will be thought wonderful that naturalists who were well acquainted with the comparative structure and development of man and other mammals should have believed that each was the work of a separate act of creation.”
This conclusion, though well known, and already famous throughout the scientific world, is here given in the proper words of the great naturalist, that the reader may see what unbounded confidence a man of science can place in himself and in his speculations. All the scientific world, excepting a few sectarian unbelievers, is against him; he knows it, and he is not dismayed. If you listen to him, his opponents are “arrogant”; they demur to his conclusion only because they pretend to be “the descendants of demi-gods.” He alone is right, he alone understands science. Buffon, Cuvier, Quatrefages, Agassiz, Elam, Frédault, and a host of other naturalists are evidently wrong. In fact, all philosophers are wrong; Mr. Darwin alone knows how to interpret scientific results; and he is so sure of this that he ventures to prophesy his approaching triumph over those benighted naturalists who, though “well acquainted with the comparative structure and development of man and other mammals,” are nevertheless so foolish as to believe that each species is the work of a separate act of creation. Such is his modesty!