Page:Popular Science Monthly Volume 45.djvu/578

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changes; changes in the constitution or substance he calls substantive variation, and these various changes may be continuous or discontinuous. The word homæosis is substituted for metamorphy—this term being applied to cases such as the eye of a crustacean developing into an antenna, or the petal of a flower into a stamen, etc. He has systematized the sports, freaks, and redundancies of Nature, and has done an amazing amount of hard work in a field to which few have been hitherto attracted. He has also emphasized in the most telling way one of the most important factors in the doctrine of natural selection—namely, variation. As to the author's conception that the discontinuity of species is at all sustained by this evidence, we can not agree. His introductory pages—and there are many of them—are as laborious reading as similar portions of Buckle's History of Civilization. Man's power of apprehension, nowadays, has so far advanced that there is no longer any necessity for iterating and reiterating self-evident propositions.

Demonstrating, as he does, sudden and spontaneous modifications in animals, he assumes, without sufficient proof, that the divergent characters of many species have originated in this way. He asks, May not specific differentiation have resulted from individual variation? The answer to this would be that if these extraordinary jumps are ever perpetuated for a time even, like the double operculum in Buccinum undatum, for example, which he cites, the wildest species-maker has never dreamed of making a separate species of such freaks. They are hardly accounted varieties.

The author says that Lamarck's view points out that living things can in some measure adapt themselves, both structurally and physiologically, to new circumstances, and that in certain cases the adaptability is present in a high degree. He also formulates Darwin's theory as showing the survival of those adapted to the environment. "According to both theories, specific diversity of form is consequent upon diversity of environment, and diversity of environment is thus the ultimate diversity of specific form. Here, then, we meet the difficulty that diverse environments often shade into each other insensibly and form a continuous series, whereas the specific forms of life which are subject to them on the whole form a discontinuous series." We should question this latter statement. We have, for example, the two great provinces of land and water; we have also marked and emphatic divergencies in these larger provinces; the deep, moist canon in an arid plain, the sharp line between light and darkness with their appropriate forms salt and fresh water, with the intermediate brackish water and the paucity of brackish water forms, and these pointing to their evident origin and subsequent adaptation; and rivers flowing through limy and granitic regions, with examples of mud lakes, sand lakes, and salt lakes. Indeed, the zones of demarcation are often so narrow that the varieties due to these selective features struggle almost hopelessly to keep up an existence.

Mr. Bateson seems to think that physical environment is the only selective action in the struggle for existence; but to those who have studied Darwin there are many other features to be taken into account, of which no mention is made. Ignoring the theory of natural selection, but recognizing the prime importance of variation as the essential phenomenon of evolution, he says, "Variation, in fact, is evolution." He overlooks the importance of all other factors upon which the theory of natural selection rests—inheritance, without which the theory would fall; the numerical proportion of individuals remaining the same, without which fact it could not be shown that an infinitely greater number of individuals perish than survive.

These equally important factors are laid aside, and he emphasizes the statement that variation, in fact, is evolution. This is as logical as if one should say evolution could not exist without life, life could not exist without oxygen (omitting certain forms of bacilli), and hence oxygen is evolution.

He repudiates the law of Von Baer, and says "it has been established almost entirely by inference, and it has been demonstrated in scarcely a single instance." Mr. Bateson can not understand why one species of moth differs a little in pattern from another species. He can not understand the utility of small differences which distinguish species. In his regard for species he should be reminded of the large number of species formerly considered good which have merged