We must, however, take care not to imitate the paradoxical reasoning of our adversaries, and because some crossings of _certain_ races are eugenesic, to conclude, _à priori_, that _all_ the other intermixtures are equally so. The study of hybridity in birds and quadrupeds has taught us that we can never know with certainty, before making the experiment, what will be the result of crossing. Neither must we forget that the ethnological facts which have served us as examples apply to the intermixture of races distinct, no doubt, but nearly related in many respects. The mixture of races more distant from each other, is it equally prolific, and are the descendants eugenesic? This is the question we now intend to examine. SECTION III. EXAMPLES TENDING TO PROVE THAT THE INTERMIXTURE OF CERTAIN RACES OF MEN ARE NOT EUGENESIC. In the first part of this essay we have endeavoured to establish that certain human cross-breeds possess an unlimited fecundity, both in their direct alliances and with either of the parent races, whence we have inferred that eugenesic hybridity really exists in mankind. We intend now to investigate the results of certain intermixtures more disparate, and review a number of facts tending to the conclusion that all human cross-breeds are not eugenesic. Let us observe at the outset, how far the phenomena of eugenesic or non-eugenesic hybridity may affect the solution of the great question pending between the Monogenists and the Polygenists. What in animals in general, characterises the eugenesic hybridity, is the unlimited fecundity of mongrels of the first degree between themselves. It is by no means necessary that the parent species should be as prolific in their crossings as in their direct unions, nor that the mongrels should be as productive as their parents, as large, as strong, and as long-lived, etc. Supposing, for instance, that the she-wolf conceives with more difficulty with the mastiff than with her proper mate; supposing even that this crossing is only efficacious by way of exception; that it succeeds only once out of ten, instead of succeeding constantly as it occurs in animals of the same species; it would be sufficient, if in this tenth case the mongrels are very prolific to pronounce the crossing eugenesic. Supposing also, that the hybrid wolf-dogs of the first degree produced only litters of about two or three, that is to say, only half the number usually produced by she-wolves and bitches, the result would be that this intermediate race would breed less rapidly by half than the pure species; but, provided the productiveness of the mongrels does not descend below the degree necessary for the preservation of the species, and provided it can repair the loss at every generation, the crossing would still be eugenesic, nor would it cease being so, even if the breed were only half as strong as their parents, and only half as long-lived.