Detlefsen's Criticism 169 



sponded precisely to the type induced by clockwise 

 or by counter-clockwise rotation in the ancestors. 



Evidently this is an important contribution to the 

 question whether a modificational change can affect 

 the progeny in a specific and representative way. We 

 must remember Herbert Spencer's emphatic declara- 

 tion: "A right answer to the question whether ac- 

 quired characters are or are not inherited underlies 

 right beliefs, not only in biology and psychology, but 

 also in education, ethics, and politics." For some 

 years the trend of opinion among zoologists has been 

 on the whole in favor of a negative answer, but the 

 results of the experiments we have referred to point 

 towards the affirmative. In such cases the proper 

 course is to repeat the experiments, and that has been 

 done by Dr. J. A. Detlefsen in his laboratory in the 

 Wistar Institute in Philadelphia, where the psycholo- 

 gists had also worked. 



What Dr. Detlefsen has to say is already sufficient 

 to suggest the need for great caution. It had been 

 noted that there was much mortality associated with 

 the previous experiments, and also a frequent occur- 

 rence of serious ear troubles. It is suggested by Dr. 

 Detlefsen that the abnormal rotation injured the 

 labyrinth of the ear and made it susceptible to mi- 

 crobic invasion. There might be an inflammation of 

 the labyrinth due to a pathogenic microbe, and this 

 might be passed on to the progeny by direct contact. 

 Moreover, less resistant offspring might be expected 

 from seriously infected parents. Dr. Detlefsen ob- 

 tained twenty rats suffering from "spontaneous" 



