Page:George Archdall Reid 1896 The present evolution of man.djvu/112

of the economy of nutrition achieved? To suppose this is to suppose that the saving of a grain or two of protein per day would determine the kangaroo's fate" (p. 14).

He next enters into elaborate arithmetical calculation concerning the eye of the proteus. "In such case the decrement would amount to ¹⁄₁₄₄₀th of the creature's weight; or, for convenience, let us say that it amounted to ¹⁄₁₀₀₀th, which would allow of the eyes being taken at some fourteen grains each. To this extent then each occasional decrement would profit the organism. The economy in weight to a creature having nearly the same specific gravity as its medium would be infinitesimal. The economy in nutrition of a rudimentary organ, consisting of passive tissues, would also be but nominal. The only appreciable economy would be in the original building up of the creature's structures; and the hypothesis of Weismann implies that the economy of this thousandth part of its weight by the decrease of the eyes, would so benefit the rest of the creature's organization as to give it an appreciably greater chance of survival, and an appreciably greater multiplication of descendants. Does any one accept this inference? " (pp. 18–9).

In reply to the above Mr. Wallace writes—

 

"The eye is treated as if it were mere protoplasm weighing so many grains, instead of being a highly complex organ, with which muscles, blood-vessels, and nerves are connected and co-ordinated in greater proportion perhaps than any other organ. I presume the original eye of the ancestral proteus must have had its three distinct sets of nerves—those of vision, of sensation, and of motion—involving in their normal use the expenditure of a considerable amount of nervous energy, besides the various muscles and blood-vessels connected with it. To measure the benefit to be