We must close here. We meant to review some of the more general scientific objections which we thought not altogether tenable. But, after all, we are not so anxious just now to know whether the new theory is well founded on facts as whether it would be harmless, if it were. Besides, we feel quite unable to answer some of these objections, and it is pleasanter to take up those which one thinks he can.
Among the unanswerable, perhaps the weightiest of the objections, is that of the absence, in geological deposits, of vestiges of the intermediate forms which the theory requires to have existed. Here all that Mr. Darwin can do is to insist upon the extreme imperfection of the geological record and the uncertainty of negative evidence. But, withal, he allows the force of the objection almost as much as his opponents urge it,—so much so, indeed, that two of his English critics turn the concession unfairly upon him, and charge him with actually basing his hypothesis upon these and similar difficulties,—as if he held it because of the difficulties, and not in spite of them;—a handsome return for his candor!
As to this imperfection of the geological record, perhaps we should get a fair and intelligible illustration of it by imagining the existing animals and plants of New England, with all their remains and products since the arrival of the Mayflower, to be annihilated; and that, in the coming time, the geologists of a new colony, dropped by the New Zealand fleet on its way to explore the ruins of London, undertake, after fifty years of examination, to reconstruct in a catalogue the flora and fauna of our day, that is, from the close of the glacial period to the present time. With all the advantages of a surface exploration, what a beggarly account it must be! How many of the land animals and plants which are enumerated in the Massachusetts official reports would it be likely to contain?
Another unanswerable question asked by the Boston reviewers is, Why, when structure and instinct or habit vary,—as they must have varied, on Darwin's hypothesis,—they vary together and harmoniously, instead of vaguely. We cannot tell, because we cannot tell why either should vary at all. Yet, as they both do vary in successive generations,—as is seen under domestication,—and are correlated, we can only adduce the fact. Darwin may be precluded from this answer, but we may say that they vary together because designed to do so. A reviewer says that the chance of their varying together is inconceivably small; yet, if they do not, the variant individuals must perish. Then it is well that it is not left to chance. As to the fact: before we were born, nourishment and the equivalent to respiration took place in a certain way. But the moment we were ushered into this breathing world, our actions promptly conformed, both as to respiration and nourishment, to the before unused structure and to the new surroundings.
"Now," says the "Examiner," "suppose, for instance, the gills of an aquatic animal converted into lungs, while instinct still compelled a continuance under water, would not drowning ensue?" No doubt. But—simply contemplating the facts, instead of theorizing—we notice that young frogs do not keep their heads under water after ceasing to be tadpoles. The instinct promptly changes with the structure, without supernatural interposition,—just as Darwin would have it, if the development of a variety or incipient species, though rare, were as natural as a metamorphosis.
"Or if a quadruped, not yet furnished with wings, were suddenly inspired with the instinct of a bird, and precipitated itself from a cliff, would not the descent be hazardously rapid?" Doubtless the animal would be no better supported than the objection. Darwin makes very little indeed of voluntary efforts as a cause of change, and even poor Lamarck need not be caricatured. He never supposed that an elephant would take such a notion into his wise head, or that a squirrel would begin with other than short and easy leaps; but might not the length of the leap be increased by practice?
The "North American" reviewer's position, that the higher brute animals have comparatively little instinct and no intelligence, is a heavy blow and great discouragement to dogs, horses, elephants, and monkeys. Stripped of their all, and left to shift for themselves as they can in this hard world, their pursuit and seeming attainment of knowledge under such peculiar difficulties is interesting to contemplate. However, we are not so sure as is the critic that instinct regularly increases downward and decreases upward in the scale of being. Now that the case of the bee is reduced to moderate proportions,[12] we know of nothing in instinct surpassing that of an animal so high as a bird, the Talegal, the male of which plumes himself upon making a hot-bed in which to hatch his partner's eggs,—which he tends and regulates the heat of about as carefully and skilfully as the unplumed biped does an eccaleobion.[13] As to the real intelligence of the higher brutes, it has been ably defended by a far more competent observer, Mr. Agassiz, to whose conclusions we yield a general assent, although we cannot quite place the best of dogs "in that respect upon a level with a considerable portion of poor humanity," nor indulge the hope, or, indeed, the desire, of a renewed acquaintance with the whole animal kingdom in a future life.[14]
The assertion, that acquired habitudes or instincts, and acquired structures, are not heritable, any breeder or good observer can refute.
That "the human mind has become what it is out of a developed instinct"[15] is a statement which Mr. Darwin nowhere makes, and, we presume, would not accept. As to his having us believe that individual animals acquire their instincts gradually,[16] this statement must have been penned in inadvertence both of the very definition of instinct, and of everything we know of in Mr. Darwin's book.
It has been attempted to destroy the very foundation of Darwin's hypothesis by denying that there are any wild varieties, to speak of, for natural selection to operate upon. We cannot gravely sit down to prove that wild varieties abound. We should think it just as necessary to prove that snow falls in winter. That variation among plants cannot be largely due to hybridism, and that their variation in Nature is not essentially different from much that occurs in domestication, we could show, if our space permitted.