arui we resume our inquiry 43 



called the psychological or mnemic theory 

 of heredity. Obviously we muct begin from 

 the biological side, for we have no direct 

 experience in the matter. Moreover it is 

 not our memory, but a so-called organic 

 memory with which we are concerned. 



Now if it is once admitted that the body 

 influences the germ-plasm in one way — i.e, 

 by way of nutrition — the possibility of its 

 influence in other ways can hardly be denied. 

 Even the influence in the one way may mean 

 a great deal more than Weismann surmised, 

 may involve not merely quantitative differ- 

 ences but qualitative differences as well. 

 Truly, as Mephistopheles said : " Blut ist ein 

 gam hesondrer Saftr For example, through 

 the blood there circulate certain secretions, 

 called hormones, destined — as our Regius 

 Professor of Medicine has said — "for the 



