76 GENETICS 



several viewpoints. For breeders, who are trying to 

 maintain or improve particular strains of animals or 

 plants; for physicians, who, in fighting disease, are 

 honestly seeking to substitute an ounce of prevention 

 for a pound of cure ; for sociologists and philanthro- 

 pists, who have at heart the permanent bettering of 

 human conditions ; for educators, who cherish hopes 

 that their life-work of unfolding the youthful mind 

 may prove cumulative and lasting rather than tran- 

 sitory; for religious workers, who want their faith 

 strengthened that conquests in character-building 

 may outreach the individual and so enrich the race ; 

 for parents, who entertain hopes that their own efforts 

 may give their children a better biological start in 

 life, — for all these and many more, it is important 

 to know the answer to the question : Can acquired 

 characters be inherited ? 



4. An Historical Sketch of Opinion 



That the personal accumulations of a lifetime are 

 heritable was generally believed all through the 

 credulous ages. A century ago Lamarck made this 

 idea the corner-stone of his theory of evolution. It 

 was all very simple. The reason evolution occurs 

 in nature is because individual acquirements are 

 being continually added to the onflowing stream 

 of living forms. This cumulation of characters 

 indeed is evolution. How else can the present stage 

 of adaptation of organisms to their several niches in 

 nature be explained save by seeing in it the final results 

 of generations of gradually inherited adaptations ? 



