hearing in another, agility in a third, and so forth; but every normal deer (and abnormality is rare among wild animals), as regards every other quality, varies a little—not much—above or below a certain mean. If the fittest survive, and we know that on the whole they do survive, it is surely clear, that those animals who in the aggregate of their essential qualities rise above the specific mean, will be those that continue the race; and since among the offspring there will be some who in the aggregate of their qualities surpass their parents, the continued survival of the fittest will in time result in evolution as regards all the other qualities.
The fundamental error is the same as that which he fell into when discussing the spurs of the Chaja screamer, and which Mr. Cunninghame fell into when discussing the horns of deer—the tacit assumption that evolution, if due to the accumulation of inborn variations, must proceed on lines of abnormal variations. Thus he writes in the passage under discussion—"But now suppose that one member of a herd—perhaps because of more efficient teeth, perhaps by great muscularity of stomach, perhaps by secretion of more appropriate gastric juices—is enabled to eat and digest a not uncommon plant which the others refuse. This peculiarity may, if food is scarce, conduce to better self-maintenance, and better fostering of the young if the individual is a hind." But is it necessary to entertain such a very improbable supposition? A deer which suddenly varies in such a manner as to be able to eat and digest a plant which the rest of its species refuse to eat and cannot digest, would be as abnormal as a mammal "with two little excrescences on its frontal bones as an occasional variation," or a bird "much given to fight," "on the wings of which thickenings of the skin occurred," "symmetrically," "at the points required," which "on their first appearance were decided enough to give appreciable
