The even-toed section of hoofed animals is a much larger group than the odd-toed, and the difference may be illustrated by looking at the great work on Natural History by Lydekker. There are 273 pages given up to this group and only 112 to the odd-toed, and when we remember that there are contained in it the hippopotamus, all the pigs, oxen, sheep, goats, antelopes, camels, llamas, giraffes and deer, we can see that Lydekker was well justified in the great amount of space devoted to them. But we all have our different forms of _penchant_, and I propose to say very much less about this section than about the other represented by the domestic horse. It is well to claim the shelter of a great name in such an apportionment of interest, and Professor Poulton has given a clear precedent in his great book called _Essays on Evolution_. It contains 393 pages and even though the subject of the work is Evolution, he has given up 330 pages approximately, or five-sixths, of his space to insects. This can be gathered from a rough analysis of his various essays, and no one need blame a great biologist for having a _penchant_ for the subject he knows best, or a small one for writing of that he knows a little. The reason that the even-toed ungulates require less study from the present point of view is that they are so much more marked by the normal or primitive slope of hair than the previous group of Chapter IX. They demonstrate very widely and thoroughly the empire of the primitive or “barbarian” forces and so far are valuable witnesses of the negative kind. No case can well be proved to satisfaction by a large series of negatives, and this was the hopeless task Weismann set out to prove, when he staked his all on the non-inheritance of acquired characters--and failed. But negative evidence is of great value in supporting an hypothesis when it is found to be the precise complement to extensive positive evidence brought in favour of that hypothesis. That is the case in regard to the patterns of hair found on oxen, sheep, antelopes, gazelles and deer, to say nothing of hippopotami, pigs and llamas. There are some of these patterns described in the previous group which appear in this larger one, but for size, persistence and frequency they cannot be compared to those of the horse, who has, if I may so say, inherited all the family property in his own person and added to it. The variations in the present group are fully dealt with in the two earlier books already quoted,[52],[53], and I will not complicate this chapter by any further remarks on them. [52] _Op. cit._ _Use inheritance._ [53] _Op. cit._ _Direction of Hair._ Oxen.