Darwin says: "A horse is trained to certain paces, and the colt inherits similar consensual movements."[39] But selection of the constitutional tendency to these paces, and imitation of the mother by the colt, may have been the real causes. The evidence, to be satisfactory, should show that such influences were excluded. Men acquire proficiency in swimming, waltzing, walking, smoking, languages, handicrafts, religious beliefs, &c., but the children only appear to inherit the innate abilities or constitutional proclivities of their parents. Even the songs of birds, including their call-notes, are no more inherited than is language by man (_Descent of Man_, p. 86). They are learned from the parent. Nestlings which acquire the song of a distinct species, "teach and transmit their new song to their offspring." If use-inheritance has not fixed the song of birds, why should we suppose that in a single generation it has transmitted a newly-taught method of walking or trotting? It is alleged that dogs inherit the intelligence acquired by association with man, and that retrievers inherit the effects of their training.[40] But selection and imitation are so potent that the additional hypothesis of use-inheritance seems perfectly superfluous. Where intelligence is not highly valued and carefully promoted by selection, the intelligence derivable from association with man does _not_ appear to be inherited. Lap-dogs, for instance, are often remarkably stupid. Darwin also instances the inheritance of dexterity in seal-catching as a case of use-inheritance.[41] But this is amply explained by the ordinary law of heredity. All that is needed is that the son shall inherit the suitable faculties which the father inherited before him. TAMENESS OF RABBITS. Darwin holds that in some cases selection alone has modified the instincts and dispositions of domesticated animals, but that in most cases selection and the inheritance of acquired habits have concurred in effecting the change. "On the other hand," he says, "habit alone in some cases has sufficed; hardly any animal is more difficult to tame than the young of the wild rabbit; scarcely any animal is tamer than the young of the tame rabbit; but I can hardly suppose that domestic rabbits have often been selected for tameness alone; so that we must attribute at least the greater part of the inherited change from extreme wildness to extreme tameness to habit and long-continued close confinement."[42] But there are strong, and to me irresistible, arguments to the contrary. I think that the following considerations will show that the greater part, if not the whole, of the change must be attributed to selection rather than to the direct inheritance of acquired habit.