226 MENTAL FACULTIES sec. 



priori have anything startling about it. That tlie supposition 

 is actually true we possess evidence in abundance, not only 

 in the facts of instinct, but in the whole mental evolution of 

 animals and of mankind. 



If the acquirement and inheritance of mental characters, 

 which can only rest upon a corporeal basis, were not possible, 

 neither man nor civilisation would exist. 



The examples which Weismann adduces in support of the 

 opposite view with regard to instinct seem to indicate, as is 

 of course only consistent on his part, that he completely 

 renounces the explanation of instinct as inherited faculties 

 and habits. This would imply that he believes in the possi- 

 bility of the evolution of all the mental faculties of animals 

 without the aid of inherited experience ; in other words, of 

 the improvement of the nervous system by inherited acquire- 

 ments. 



Weismann appeals to cases " in which degenerations may 

 affect only a single instinct, while the animal remains com- 

 pletely unaffected thereby in its general form and general 

 functions." 



He mentions that the instinct of flight possessed by the 

 wild ancestors of our domesticated animals has in the latter 

 more or less completely disappeared. But he says the case 

 of guinea-pigs shows how slowly this instinct disappears 

 under domestication ; ever since the discovery of America, 

 that is, for about four hundred years, have they been 

 dependent on man, and they still start at every loud noise 

 and try to flee. I have always referred to guinea-pigs as 

 an instance of animals whose wild originals are entirely 

 unknown, as unknown as those of the gold-fish, and which, 

 like the latter, have probably been maintained from time 

 immemorial and still exist only under the j)rotection of man. 

 If this be so, the peculiarity referred to by Weismann is still 

 more in his favour. I know well this characteristic of guinea- 



