We should expect that our domesticated plants and animals should vary most, inasmuch as these have been subjected to changed conditions which would disturb the memory, and, breaking the chain of recollection, through failure of some one or other of the associated ideas, would thus directly and most markedly affect the reproductive system. Every reader of Mr. Darwin will know that this is what actually happens, and also that when once a plant or animal begins to vary, it will probably vary a good deal further; which, again, is what we should expect—the disturbance of the memory introducing a fresh factor of disturbance, which has to be dealt with by the offspring as it best may. Mr. Darwin writes: “All our domesticated productions, with the rarest exceptions, vary far more than natural species” (“Plants and Animals,” &c., vol. ii. p. 241, ed. 1875). On my third supposition, _i.e._, when the difference between parents has not been great enough to baffle reproduction on the part of the first cross, but when the histories of the father and mother have been, nevertheless, widely different—as in the case of Europeans and Indians—we should expect to have a race of offspring who should seem to be quite clear only about those points, on which their progenitors on both sides were in accord before the manifold divergencies in their experiences commenced; that is to say, the offspring should show a tendency to revert to an early savage condition. That this indeed occurs may be seen from Mr. Darwin’s “Plants and Animals under Domestication” (vol. ii. p. 21, ed. 1875), where we find that travellers in all parts of the world have frequently remarked “_on the degraded state and savage condition of crossed races of man_.” A few lines lower down Mr. Darwin tells us that he was himself “struck with the fact that, in South America, men of complicated descent between Negroes, Indians, and Spaniards seldom had, whatever the cause might be, a good expression.” “Livingstone” (continues Mr. Darwin) “remarks, ‘It is unaccountable why half-castes are so much more cruel than the Portuguese, but such is undoubtedly the case.’ An inhabitant remarked to Livingstone, ‘God made white men, and God made black men, but the devil made half-castes.’” A little further on Mr. Darwin says that we may “perhaps infer that the degraded state of so many half-castes _is in part due to reversion to a primitive and savage condition_, _induced by the act of crossing_, even if mainly due to the unfavourable moral conditions under which they are generally reared.” Why the crossing should produce this particular tendency would seem to be intelligible enough, if the fashion and instincts of offspring are, in any case, nothing but the memories of its past existences; but it would hardly seem to be so upon any of the theories now generally accepted; as, indeed, is very readily admitted by Mr. Darwin himself, who even, as regards purely-bred animals