226 A STUDY IN HEREDITY 



plain that that which is acquired by the parent does not become 

 inborn in the child. 



It may, however, be maintained by Neo-Lamarckians that 

 stimulation causes not only the acquirement of a character, but 

 increases also the power of acquiring it, and that it is this increase 

 in the parent that is transmitted to the child, and which renders 

 more easy the acquirement of the character by the latter. But 

 there is no tittle of evidence showing that the stimulation which 

 results in the acquirement of a character (mental or physical) 

 causes also an increase in the power of acquiring it. The 

 converse is in fact true : the infant's power of acquiring characters, 

 mental and physical, is immense, and to it is mainly owing the 

 development he undergoes in his passage from infancy to old age. 

 But this power steadily declines in his long stimulated parts 

 (mental and physical), till in the old man it is reduced to a 

 minimum and tends to vanish. Clearly, then, as regards such 

 characters as result from use and experience there can be no 

 transmission to the child; therefore, as regards them, evolution 

 must have proceeded wholly on lines of Natural Selection. More- 

 over, instincts (and such physical characters as are analogous to 

 instincts, i.e. inborn physical parts) cannot have resulted from the 

 transmitted effects of experience and use, since they do not 

 increase under stimulation. There is, for instance, no reason to 

 suppose that any instinct is sharpened by use, or, in other words, 

 by experience. In fact, it would be a contradiction in terms to 

 suppose that it is, since, if my definitions are right, all that is 

 acquired pertains to reason, not to instinct. Moreover, did 

 instincts increase under stimulation, and were this increase trans- 

 missible in however slight a degree, then instincts should be most 

 developed in the highest animals and less in lower animals. The 

 contrary, however, is the fact. 



All acquired mental characters depend, of course, in the last 

 analysis, on memory ; and, therefore, an animal which is incapable 

 of acquiring mental characters, and which, therefore, depends 

 wholly on instinct, can have no recollection of past events, nor, 

 as a consequence, any ideas concerning the future ; it must live 



