VIII. If, then, memory depends on association, we should expect two corresponding phenomena in the case of plants and animals—namely, that they should show a tendency to resume feral habits on being turned wild after several generations of domestication, and also that peculiarities should tend to show themselves at a corresponding age in the offspring and in the parents. As regards the tendency to resume feral habits, Mr. Darwin, though apparently of opinion that the tendency to do this has been much exaggerated, yet does not doubt that such a tendency exists, as shown by well authenticated instances. He writes: “It has been repeatedly asserted in the most positive manner by various authors that feral animals and plants invariably return to their primitive specific type.” This shows, at any rate, that there is a considerable opinion to this effect among observers generally. He continues: “It is curious on what little evidence this belief rests. Many of our domesticated animals could not subsist in a wild state,”—so that there is no knowing whether they would or would not revert. “In several cases we do not know the aboriginal parent species, and cannot tell whether or not there has been any close degree of reversion.” So that here, too, there is at any rate no evidence _against_ the tendency; the conclusion, however, is that, notwithstanding the deficiency of positive evidence to warrant the general belief as to the force of the tendency, yet “the simple fact of animals and plants becoming feral does cause some tendency to revert to the primitive state,” and he tells us that “when variously-coloured tame rabbits are turned out in Europe, they generally re-acquire the colouring of the wild animal;” “there can be no doubt,” he says, “that this really does occur,” though he seems inclined to account for it by the fact that oddly-coloured and conspicuous animals would suffer much from beasts of prey and from being easily shot. “The best known case of reversion:” he continues, “and that on which the widely-spread belief in its universality apparently rests, is that of pigs. These animals have run wild in the West Indies, South America, and the Falkland Islands, and have everywhere re-acquired the dark colour, the thick bristles, and great tusks of the wild boar; and the young have re-acquired longitudinal stripes.” And on page 22 of “Plants and Animals under Domestication” (vol. ii. ed. 1875) we find that “the re-appearance of coloured, longitudinal stripes on young feral pigs cannot be attributed to the direct action of external conditions. In this case, and in many others, we can only say that any change in the habits of life apparently favours a tendency, inherent or latent, in the species to return to the primitive state.” On which one cannot but remark that though any change may favour such tendency, yet the return to original habits and surroundings appears to do so in a way so marked as not to be