74 Can Science Explain Life? 



to the cerebral cortex instead of being dissipated 

 and lost in the surrounding tissues. 



It is a significant fact that thoughts and memo- 

 ries are never transmitted through the germ cells 

 by inheritance. If thoughts and memories were 

 self-contained entities, such as chemical sub- 

 stances, then they would be carried by the proto- 

 plasmic or blood circulation to all parts of the 

 organism and would eventually reach the germ 

 cells and be transmitted to the next generation, 

 whereas no trace of one's thoughts or memories 

 has ever been inherited. It appears, therefore, 

 that we must regard thoughts and memories not 

 as substances but rather as manifestations of the 

 behavior of certain chemical structures of the 

 central nervous system which have become altered 

 or activated by sensory impulses during the life 

 of the individual. During embryonic life and for 

 some time thereafter the effects of such sensory 

 impulses are rapidly obliterated by cell division 

 and memory is then of only short duration, but 

 during adult life there is only very little, if any, 

 cell division in the central nervous system so that 

 the impressions which are then produced by sen- 

 sory impulses will remain for an indefinite time. 



The transmission of impulses through nerve- 

 fibers can take place in no other way than by 

 electrolytic conduction along the polygonal com- 



