244 GARY N. CALKINS. 



mental work on Paramecium artificial parthenogenesis was suc- 

 cessful at three different periods of depression but failed on the 

 fourth, and we may infer that normal parthenogenesis has only 

 a limited success and that sooner or later the race must come to 

 an end unless conjugation and nuclear reorganization take place. 

 It is conceivable that parthenogenesis is only a means of offsetting 

 physiological death or in other words, of stimulating physiological 

 activities in protoplasm in which the potential of development is 

 not yet exhausted. 



