"We may also include in the same category those algae and fungi which have bright colours—the red snow of the Arctic regions, the red, green, or purple seaweeds, the brilliant scarlet, yellow, white or black agarics, and other fungi. All these colours are probably the direct results of chemical composition or molecular structure, and being thus normal products of the vegetable organism, need no special explanation from our present point of view; and the same remark will apply to the varied tints of the bark of trunks, branches and twigs, which are often of various shades of brown and green, or even vivid reds and yellows[138]."
Here, as Mr. Gulick has already observed, "Mr. Wallace seems to admit that instead of useless specific characters being unknown, they are so common and so easily explained by 'the chemical constitution of the organism' that they claim no special attention[139]." And whatever answer Mr. Wallace may make to this criticism, I do not see how he is to meet the point at present before us—namely, that, upon his own showing, there are in nature numberless instances of "characters which are useless without being hurtful," and which nevertheless present absolute "constancy." If, in order to explain the contradiction, he should fall back upon the principle of correlation, the case would not be in any way improved. For, here again, if the term correlation were extended so as to include "the chemical constitution or the molecular structure of the organism," it would thereby be extended so as to discharge all Darwinian significance from the term.
Summary.
I will conclude this discussion of the Utility question by recapitulating the main points in an order somewhat different from that in which they have been presented in the foregoing chapters. Such a variation may render their mutual connexions more apparent. But it is only to the main points that allusion will here be made, and, in order the better to show their independent character, I will separately number them.
1. The doctrine of utility as universal, whether with respect to species only or likewise with respect to specific characters, is confessedly an a priori doctrine, deduced by way of general reasoning from the theory of natural selection.
2. Being thus founded exclusively on grounds of deduction, the doctrine cannot be combated by any appeal to facts. For this question is not one of fact: it is a question of reasoning. The treatment of our subject matter is logical: not biological.
3. The doctrine is both universal and absolute. According to one form of it all species, and according to another form of it all specific characters, must necessarily be due to the principle of utility.
4. The doctrine in both its forms is deduced from a definition of the theory of natural selection as a theory, and the sole theory, of the origin of species; but, as Professor Huxley has already shown, it does not really follow, even from this definition, that all specific characters must be "necessarily useful." Hence the two forms of the doctrine, although coincident with regard to species, are at variance with one another in respect of specific characters. Thus far, of course, I agree with Professor Huxley; but if I have been successful in showing that the above definition of the theory of natural selection is logically fallacious, it follows that the doctrine in both its forms is radically erroneous. The theory of natural selection is not, accurately speaking, a theory of the origin of species: it is a theory of the origin and cumulative development of adaptations, to whatever order of taxonomic division these may happen to belong. Thus the premisses of the deduction which we are considering collapse: the principle of utility is shown not to have any other or further reference to species, or to specific characters, than it has to fixed varieties, genera, families, &c., or to the characters severally distinctive of each.
5. But, quitting all such antecedent considerations, we next proceeded to examine the doctrine a posteriori, taking the arguments which have been advanced in favour of the doctrine, other than those which rest upon the fallacious definition. These arguments, as presented by Mr. Wallace, are two in number.