Facts and Factors of Development 45 



of some chemical substance which remains in the protoplasm for 

 a certain time, during which time the effects of the stimulus are 

 said to persist, or it may he due to some physical change in the 

 protoplasm analogous to the "set" in metals which have been 

 subjected to mechanical strain. 



Organic Memory. — Probably of a similar character is the per- 

 sistence of the effects of repeated stimuli and responses on any 

 organ of a higher animal. A muscle which has contracted many 

 times in a definite way ultimately becomes "trained" so that it 

 responds more rapidly and more accurately than an untrained 

 muscle ; and the nervous mechanism through which the stimulus 

 is transmitted also becomes trained in the 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 

 difficult art of talking, is probably due to the persistence in mus- 

 cles and nerves of the effects of many previous activities. All 

 such phenomena were called by Hering "organic memory," to in- 

 dicate 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 com- 

 monly call memory. 



Associative Memory. — It seems probable that this ability of pro- 

 toplasm 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, develops associative and conscious memory in the ma- 

 ture organism. 



4. Intellect, Reason. — Even the intellect and reason which SO 

 strongly characterize man have had a development from rela- 



