10 SOCIAL HEREDITY AND SOCIAL EVOLUTION 



factor has been the repetition in the offspring oi i\u: 

 characteristics of the parents, a phenomenon that 

 we call heredity. This has so clearly been the funda- 

 mental force as to have led to most extended studies 

 aimed at solving the method of its action. Darwin 

 tried to form an idea of its mechanism, but with 

 little success. Various others have attempted the 

 same thing with equal lack of success, until the 

 simple suggestion of Weismann, about thirty years 

 ago, placed it in an entirely new light. His concep- 

 tion of a continuous germinal substance so clearly 

 fulfilled the requirements as to place AVeismann's 

 explanation of heredity beyond the class of mere 

 theories and to put it among the accepted truths of 

 science. With increasing interest and avidity as 

 newly discovered facts began to disclose fundamen- 

 tal laws, has the subject of heredity been studied for 

 three decades. Out of the accumulated facts some 

 clearly definite results have already been reached. 

 1, It has been quite firmly demonstrated that the 

 class of characters which we commonly call acquired 

 are not passed on to the offspring by inheritance. 

 Animals may transmit to their offspring those traits 

 that they themselves have inherited, but they cannot 

 transmit those characters that they have developed 

 in themselves as the result of their own actions, or 

 as the result of the action of their environment upon 

 them. It has been difficult to make us willing to 

 accept this conclusion; for we have generally been 

 unwilling to believe that our own actions cannot in 

 any degree affect the characteristics that we trans- 

 mit to our children. But the accumulating evidence 

 has finally forced us to give up the cherished belief 

 in the inheritance of acquired characters. 2. The 



