In the evolution of our breeds of domesticated animals, germinal selection in the negative sense must also have played a part--I mean through the weakening and degeneration of individual determinants. Only in this way, it seems to me, can we explain the tameness of our domestic animals, dogs, cats, horses, &c., in which all the instincts of wildness, fleeing from Man, the inclination to bite, and to attack, have at least partly disappeared. It is, of course, very difficult to estimate how much of this is to be ascribed to acquired habitude during the individual lifetime. The case of the elephant might be cited in evidence of tameness which arises in the individual lifetime, for all tame elephants are caught wild, but it seems that captured young beasts of prey, such as the fox, wolf, and wild cat, not to speak of lions and tigers, never attain to the degree of tameness exhibited by many of our domesticated dogs and cats. The very considerable differences in the degree of tameness of dogs and cats go to show that the case is one of instincts varying in different degree. If this be so, then the instinct of wildness, if I may express myself so for the sake of brevity, has degenerated in consequence of its superfluity, and through the process of germinal selection, which allowed the determinants of the brain-parts concerned to set out on a path of downward variation upon which they met with no resistance on the part of personal selection. Herbert Spencer adduced against my position the case of the reduction in the size of the jaws in many breeds of dog, especially in pugs and other lap-dogs, which he regarded as evidence of the inheritance of acquired characters. But this and analogous cases of the degeneration of an organ during a long period in which the animal had been withdrawn from the conditions of natural life is intelligible enough on the assumption of persistent germinal selection aided by panmixia. The jaws and teeth in these spoilt pets no longer require to be maintained at the level of strength and sharpness essential to their ancestors which depended on these characters, and so they fell below it, became smaller and weaker, but could not disappear altogether, for the process of degeneration was brought, or is being brought, to a standstill by the intervention of personal selection.