124 THE DIRECT INFLUENCE 



to the manner in which the formation of the new 

 characters was induced. The experimental agen- 

 cies employed affected both the soma and the 

 germ-plasm segregated in the reproductive ele- 

 ments, and no interpretation of the facts would 

 justify the conclusion that the aberrant quahties 

 were somatogenically acquired. 



While failure has attended all eflforts to dem- 

 onstrate the continued inheritance of impressions 

 received by the body alone, a number of arrange- 

 ments are found in nature which seem to demand 

 such action for their explanation. Among these 

 certain rudimentary organs, and also co-adapta- 

 tions in which simultaneous specialization occur- 

 ring in two or more members of the body has 

 made for increased fitness, are difficult of inter- 

 pretation without the interposition of somatic 

 induction. 



DIRECT STIMULATION OF THE GERM-PLASM 

 IN BEETLES 



Meanwhile the possibility of influencing hered- 

 ity by agencies acting directly upon the germ- 

 cells has awakened the keenest interest among 

 biologists. The relations of soma and germ- 

 plasm make it difficult to induce changes in the 

 body without affecting the reproductive elements, 

 while it is possible to devise experimental meth- 

 ods by which the egg or sperm alone may be sub- 

 jected to modifying agencies. This has been 

 done with such success that some very important 



