페이지 이미지
PDF
ePub

recipe for making an "eye,” which we commend to the reader's special attention. It is as follows:

“It is scarcely possible to avoid comparing the eye to a telescope.-If we must compare the eye to an optical instrument, we ought, in imagination, to take a thick layer of transparent tissue, with a nerve sensitive to light beneath, and then suppose every part of this layer to be continually changing in density, so as to separate into layers of different densities and thicknesses, placed at different distances from each other, and with the surfaces of each layer slowly changing in form. Further, we must suppose that there is a power always intently watching each slight accidental alteration in the transparent layers; and carefully selecting each alteration which, under varied circum

image. We must suppose each new state of the instrument to be multiplied by the million; and each to be preserved till a better be produced, and then the old ones to be destroyed. In living bodies, variation will cause the slight alterations ; generation will multiply them almost infinitely, and natural selection will pick out with unerring skill each improvement."

He remarks, in this connection, on page 168:

“I can see no very great difficulty, (not more than in the case of other structures) in believing that Natural Selection has converted the simple apparatus of an optic nerve, coated with pigment and invested by transparent membrane, into an optical instrument, as perfect as is possessed by any member of the great Articulate class.”

In the next sentence he says :

“He who will go thus far, ought not to hesitate to go further, and to admit, that a structure even as perfect as the eye of an eagle might be formed by Natural Selection, although in this case he does not know any of the transitional grades.”

And then adds, with sublime coolness :-"His reason ought to conquer his imagination.”!

Upon the strength of such reasoning, he requires the reader to admit that “there is no logical impossibility in the acquirement of any conceivable degree of perfection, through Natural Selection."

Every reader of Mr. Darwin's book must be struck with one peculiarity, which characterizes his mode of argumentation, or manner of handling his subject,for it can hardly be called reasoning, even by courtesy. It consists in the use of the term, “Natural Selection,” in connection with such expressions as, "I can see no difficulty,"_“It is conceivable,”—“We may

suppose,” or “I have no doubt,”-occurring on almost every page, and constantly advanced in explanation of all the mysteries of nature, without the slightest regard to logical sequence.

Thus the difficulties of a question are stated and re-stated, with many facts, opinions, and much irrelevant matter, and then the most astounding conclusion is drawn from a very frivolous premiss, or the most sweeping generalization is based on a flimsy foundation, which, coupled with the above stereotyped expression, is offered as a full and logical solution of the whole difficulty. We will give but two instances, out of a host.

The constant re-production, in every community of bees and ants, of working neuters, presenting a fixed structure different from their parents, is a mystery which is fatal to his hypothesis ; for this peremptorily demands that the acquisition and perpetuation of any given form, shall be the effect of direct inheritance. His hypothesis, therefore, will not apply to those forms the possessors of which are sterile. “But,” says Mr. Darwin, “some insects, in a state of nature, occasionally become sterile ;" this is his premiss, -and the conclusion which he immediately draws from it is this :

"And if such insects had been social, and (if) it had been profitable to the community that a number should have been annually born, capable of work, but incapable of procreation, I can see no very great difficulty in this being effected by Natural Selection.”—p. 209.

Nor can any one else, if “Natural Selection” have the same power as God Almighty.

Again,-he learns from Mr. Hearne, that a black bear was seen swimming, for hours, with widely open mouth,-probably overheated by running, and cooling himself. His assumption is, that he was "thus catching, like a whale, insects in the water." His generalization of this odd freak of a bear, and its supposed motive, is, that black bears may become the progenitors of a whale-like progeny. He says :

“Even in so extreme a case as this, if the supply of insects were constant, and if better adapted competitors did not already exist in the country, I can see no difficulty in a race of bears being rendered, by Natural Selection, more and more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale.”—p. 165.

Mr. Darwin's own inability to see any difficulty in nature which his Natural Selection cannot remove, is always his strongest argument to induce others to accept his hypothesis.

The examples, as well as the reasoning, by which he seeks to inculcate his doctrine, in the way of illustration, insinuation, or indirect support, are extremely lame and impotent, not to say frivolous. Thus, for instance, from the fact that a woodpecker has been occasionally seen feeding on fruit, or catching insects in the air or on the ground, he would have us to conclude that this bird was not originally formed to climb trees and bore for insects, but that this faculty was conferred on it by Natural Selection. In proof, he tells us that he had once seen a bird which he considered to be a wood-pecker, [mark the evidence,] inasmuch as it looked and flew very much like a wood-pecker, but " which never climbs a tree,” [mark the proof,] for he met with it “on the plains of La Plata, where not a tree grows."-p. 165. Thus he cites the frigate-bird, as being web-footed, yet never alighting on the water, (a mistake,] and also the grebe and coot, which are eminently aquatic, “although their toes are only bordered by membrane,”-as proof that these birds are being transmuted, by Natural Selection, into different species. He says, “In the frigate-bird, the deeply scooped membrane between the toes shows that the structure has begun to change.” In like manner, he would have us come to the same logical conclusion of transmutation by Natural Selection, because “there are upland geese, with webbed feet, which rarely or never go near the water,"_and because, petrels, the most aërial of birds, and water-ouzels, which belong to the thrush family, dive and swim, (as he asserts,) like auks or grebes.

So also the existence of rudimentary front teeth in calves is advanced as convincing proof that some ancient cow, who had lost her front teeth, or who had laid them aside by “disuse," finding that she could get along better with tongue and palate, was the progenitrix of all cattle which have no upper front teeth. In like manner, from the rudimentary teeth of foetal whales, he insinuates their terrestrial origin-probably from bears, as before stated. So also, as the tail is an organ of motion in fishes, he argues that Natural Selection has modified the shape, but preserved the same use in terrestrial animals of aquatic origin; thus in dogs, (he says, the tail enables them to turn quicker, though he admits that the hare, with hardly any tail, turns readily enough.

Mr. Darwin's book is not a work of scientifically applied facts in proof of a theory, but is, principally, a diffuse and very illogical argument, based on a misapplication of known facts, by which he seeks, first, to support his gratuitous assumptions, and then, by a fanciful not to say absurd application of his assumptions to more obscure facts, he attempts, at the same time, to establish his hypothesis, and also to claim for it the merit of explaining these obscurities.

Giving free scope to a lively imagination, inherited, doubtless, from his grand-father, the celebrated author of the “Loves of the Plants,” Mr. Darwin has generalized from his assumptions, and has thus devised an hypothesis, which makes men and brutes all but self-existent, since they are self-created from simple monads, upwards.

Thoroughly, and we doubt not, honestly convinced of its truth, he asserts its competency to explain all the mysteries of creation more satisfactorily than any other theory, and he can see no difficulty, under its illumination, in accounting for the most obscure phenomena of nature. It is, however, in regard to the origin and extinction of those ancient forms of life which Geology discloses, that Mr. Darwin claims for his hypothesis special merit. He thinks he has at length solved this difficult problem. Let us carefully test this claim.

Geology teaches, with great distinctness, the successive changes which have modified the surface of the earth—from that state in which no trace of organization can be discovered, up to its present condition, teeminy with varied forms of life. It also records the successive appearance of different forms of organized beings, advancing in the scale of creation, from the simplest cellular plants and plant-like animals, entombed in the deepest rocks of the earth, to man, whose origin cannot be traced beyond the dust and “drift” which cover its present surface. It also reveals the fact that each race, as it came into existence, was admirably adapted to the physical condition of the earth at the time of its appearance, to the place it was designed to fill, and the functions it was called upon to discharge.

This is the catholic creed of Geologists, whether they believe in Revelation or not. Preparation, plan, and nice adaptation, mark every stage of the world's progress. “Nor is it only the PLAN of the great types, (to use the words of Agassiz,) which must have been adopted from the beginning, but also the manner in which these plans were to be executed ; the systems of form under which these structures were to be clothed, and even the ultimate details of structure which, in different genera, bear definite relations to those of other genera ; the mode of differentiation of species, and the nature of their relations to the surrounding media, must likewise have been determined,for the character of the classes is as well defined as that of the four great branches of the animal kingdom, or that of the families, the genera, and the species." He also expresses the conviction, that the whole creation is the expression.of a thought, and not the product of physical agents,"

The four great types referred to above, present characteristic structural differences, which were as fixed and determinate in the earliest animals which Geology reveals, as they are in those of the present day.

By adding to these great types the lowest form of animal life, we have five great divisions of the Animal Kingdom, under which every animal that has ever lived may be ranked, and which may be specified, beginning at the lowest, as, I. Protozoans ; II. Radiates ; III. Molluscs ; IV. Articulates, and V. Vertebrates.

How many and which genera or species, comprised in each of these great divisions, were original and independent creations, what developments or modifications from external causes these primordial genera or species have undergone, will probably, as we have before said, always be a matter of doubt and dispute.

« 이전계속 »