64 HEREDITY AND ENVIRONMENT 



same way. Indeed such training is probably 

 chiefly a training of the nervous mechanism. 

 The skill of the pianist, of the tennis player, 

 of the person who has learned the difficult art 

 of standing and walking, or the still more diffi- 

 cult art of talking, is probably due to the per- 

 sistence in muscles and nerves of the effects 

 of many previous activities. All such phe- 

 nomena were called by Hering "organic 

 memory," to indicate that this persistence of 

 the effects of previous activities in muscles and 

 other organs is akin to that persistence of the 

 effects of previous experiences in the nervous 

 mechanism which we commonly call memory. 

 It seems probable that this ability of proto- 

 plasm in general to preserve for a time the 

 effects of former stimuli is fundamentally of 

 the same nature as the much greater power of 

 nerve cells to preserve such effects for much 

 longer periods and in complex associations, a 

 faculty which is known as associative memory. 

 The embryos, and indeed even the germ cells 

 of higher animals, may safely be assumed to 

 be endowed with protoplasmic and organic 

 memory, out of which, in all probability, de- 



