spondingly slow. To take an example—a buck and a doe antelope, whose sight and hearing respectively are keener than the average, but whose other qualities are equal to the mean of the species, are at an advantage as regards the sense of sight and hearing respectively. If they mate, the offspring, while attaining to the specific mean in the other qualities, will in general surpass it as regards sight and hearing, but will fall below the male parent as regards the sight, and the female parent as regards the hearing; for the comparative dullness of the male's hearing will militate in the offspring against the keenness of the female's hearing, and vice versa as regards the sight. So also with the offspring of a buck pre-eminent for endurance and a doe pre-eminent for speed. Then, if the offspring of the two pairs mate, their offspring will surpass, but in a lessening degree, the specific mean in keenness of sight and hearing, in speed and in endurance, but will fall below each of the grandparents as regards the one quality in which that grandparent excelled, though they will surpass each of them as regards all the other qualities. Therefore if the essential qualities are numerous,—and they always are so in the case of wild animals,—the descendants of numerous ancestors, each one of whom was pre-eminent in one of these qualities, will tend more and more, generation after generation, to approach the general racial mean as regards all these qualities;—which appears to lead to the absurd conclusion, that in the end there will be no evolution at all. But in coming to that conclusion we shall have forgotten that the offspring never present an exact mixture of the qualities of the parents, but that spontaneous variations, caused we know not how, continually arise, in consequence of which one or more of the offspring of the keen-sighted father and the quick-hearing mother (for instance) may surpass both parents
