ness in itself. The tamest mothers would also be less liable to neglect or devour their offspring, as rabbits commonly do when their young are handled too soon, or even when merely frightened. by mice, &c., or disturbed by changed surroundings. (3) We must remember the extraordinary fecundity of the rabbit and the excessive amount of elimination that consequently takes place either naturally or artificially. Where nature preserved only the wildest, man has preserved the tamest. If there is any truth in the Darwinian theory, this thorough and long-continued reversal of the selective process must have had a powerful effect. Why should it not be amply sufficient to account for the tameness and mental degeneracy of the rabbit without the aid of a factor which can readily be shown to be far weaker in its normal action than either natural or artificial selection? Why may not the tameness of the rabbit be transferred to the group of cases in which Darwin holds that "habit has done nothing," and selection has done all? (4) If use-inheritance has tamed the rabbit, why are the bucks still so mischievous and unruly? Why is the Angora breed the only one in which the males show no desire to destroy the young? Why, too, should use-inheritance be so much more powerful in the rabbit than with other animals. which are far more easily tamed in the first instance ? Wild young rabbits when domesticated "remain unconquerably wild," and, although they may be kept alive, they pine and "rarely come to any good." Yet the animal which acquires least tameness or apparently, indeed, none at allinherits most! It appears, in fact, to inherit that which it cannot acquire-a circumstance which indicates the selection of spontaneous variations rather than the inheritance of changed habits. Such variations occasionally occur in animals in a marked degree. Of a litter of wolf-cubs, all brought up in the same way, one became tame and gentle like a dog, while the others preserved their natural savagery." Is it not probable that permanent domestication was rendered possible by the inevitable selection of spontaneous variations in this direction? The excessive tameness, too, of the young rabbit, while easily explicable as a result of unconscious selection, is not easily explained as a result of acquired habit. No particular care is taken to tame or teach or domesticate rabbits. They are bred for food, or for profit or appearance, and they are left to themselves most of their time. As Sir J. Sebright notices with some surprise, the domestic rabbit "is not often visited, and seldom handled, and yet it is always tame." G MODIFICATIONS OBVIOUSLY ATTRIBUTABLE TO SELECTION. Innumerable modifications in accordance with altered use or disuse, such as the enlarged udders of cows and goats, and the diminished lungs and livers in highly bred animals that take little exercise, can be readily and fully explained as depending on selection. As the fittest for the natural or artificial requirements will be favoured, natural or artificial selection may easily enlarge organs that are increasingly used and economize in those that are less needed. I therefore see no necessity whatever for calling in the aid of use-inheritance as Darwin does, to account for enlarged udders, or diminished lungs, or the thick arms and thin legs. of canoe Indians, or the enlarged chests of mountaineers, or the diminished eyes of moles, or the lost feet of certain beetles, or the reduced wings of logger-headed ducks, or the prehensile tails of SIMULATION BY NATURAL SELECTION. 83 monkeys, or the displaced eyes of soles, or the altered number of teeth in plaice, or the increased fertility of domesticated animals, or the shortened legs and snouts of pigs, or the shortened intestines of tame rabbits, or the lengthened intestines of domestic cats, &c.1 Changed habits and the requisite change of structure will usually be favoured by natural selection; for habit, as Darwin says, "almost implies that some benefit great or small is thus derived." SIMILAR EFFECTS OF NATURAL SELECTION AND USE-INHERITANCE. Here we perceive a difficulty which will equally trouble those who affirm use-inheritance and those 1 Origin of Species, pp. 188, 110; Descent of Man, pp. 32-35; Variation of Animals and Plants under Domestication, ii. 289, 293. Use or disuse during lifetime of course co-operates, and in some cases, as in that of the canoe Indians, may be the principal or even perhaps the sole cause of the change. |