140 



ROBERT H. HUTCHISON 



ably the exhaustion of food supply, gradually arose, which inter- 

 fered with the development of the animals. Race 5 disappeared 

 entirely at the end of the two months while Races 1 and 6 main- 

 tained themselves a few weeks longer. Although Race 5, under 

 the influence of some unknown condition, disappeared much 

 sooner than the others, yet its resistance during its early healthy 

 period of rapid development was just the same as that during 

 the later period of depression. For example^ one experiment on 



TABLE 7 

 • Paramecium, caudatum Pure line no. 1 



TABLE 8 



Paramecium caudatum Pure line no. 5 



TABLE 9 4 



Paramecium caudatum Pure line no. 6 



