Huxley describes the attitude towards the theory in the year following the publication of the _Origin of Species_: “In the year 1860 there was nothing more volcanic, more shocking, more subversive of everything right and proper, than to put forward the proposition that, as far as physical organisation is concerned, there is less difference between man and the highest apes than there is between the highest apes and the lowest.... That question was not a pleasant one to handle.” But the “horrible paradoxes of one generation became the commonplaces of schoolboys”; and the “startling proposition” of 1860 was, twenty years later, a “fact that no rational man could dispute.”[42] Footnote 42: Add. Brit. Ass., 1878, Dublin. This question of the difference between man and the apes was embittered by the personal encounter between Huxley and Owen. Professor Owen, in 1857, stated that the _hippocampus minor_, which characterises the hind lobe in each hemisphere in the human brain, is peculiar to the genus _Homo_. This Huxley denied;[43] and, as neither disputant would acknowledge that he was mistaken, the question became “one of personal veracity.” Footnote 43: “It is not I who seek to base man’s dignity upon his great toe, or to insinuate that we are lost if an ape has a _hippocampus minor_.”—_Anth. Rev._, I., 113. As a possible explanation of this famous dispute, it is interesting to note the discovery announced by Professor D. J. Cunningham of the absence of this cavity on one side of the brain of an orang-utan, with the suggestion that Owen “may in the first instance have been misled by an abnormal brain of this kind.”[44] Footnote 44: Cunn. Mem., II., R.I.A., p. 128. The further history of the development, expansion, and curtailment of the Darwinian theory as such lies beyond the scope of this little book. The criticisms of sexual selection and of the origin of the higher mental characters of man by Wallace; the denial of the inheritability of acquired characters by August Weismann and others; the orthogenesis theory of Theodore Eimer, the “mutation” theory of Hugo de Vries and Mendel’s researches—all opened up lively controversies, and the field of science is still clouded with the smoke of their battles.