106 BIOLOGY AND SOCIAL PROBLEMS 



skin cells, for instance, can so influence the 

 germ cells of the same animal as to produce 

 the newly acquired trait in its offspring. That 

 the germ cells are influenced by the somatic 

 cells there can be not the least doubt, but 

 that this influence shall result in repro- 

 ducing in the somatic cells of the offspring 

 exactly the condition acquired by the cor- 

 responding cells of the parents is almost in- 

 conceivable. Since there is no known means 

 either in descent or otherwise of transferring 

 the changes which occur in the somatic cells 

 of an individual to its own germ cells so as 

 to insure that these changes may be handed on 

 as such to its offspring, Weismann was led to 

 suspect that acquired characters were not in- 

 herited, and that, therefore, the Lamarckian 

 hypothesis, natural and simple as it appeared 

 on the surface, was untenable. 



The experimental evidence that has been 

 gathered concerning this question has been 

 largely in support of Weismann's contention. 

 One of the first lines of experimental work to 

 be instituted in this direction was that on mu- 

 tilations. The tails of rats and mice were cut 

 off generation after generation with the inten- 

 tion of discovering whether this process tended 



