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RAYMOND PEARL 



great majority if not, indeed, practically all of the offspring 

 are in some degree defective. This condition of affairs I have 

 tried to represent very roughly diagramatically in figure 5. The 

 cross-hatched portion of the area (A') represents the sperm (or 

 ova) which are definitely out of commission so far as taking 

 part in zygote formation, either because of their inherent weak- 

 ness or because of the action of the alcohol, or both. The singly 

 ruled portion (6') represents the germ cells which form zygotes 

 but have been so weakened by the alcohol that these zygotes 

 are in some degree defective. 



3 4 5 6 7 



Fig. 5 For explanation see text. 



3 4 5 6 7 



Fig. 6 For explanation see text. 



A less extreme relationship between effective dosage of the 

 agent, P, and the resisting power of the germ cells is shown in 

 figure 6. In this diagram it will be seen that a very small part 

 of the total area falls in the a' class, which represents germ 

 cells of such high resisting power as not to be detectibly affected 

 by the deleterious agent. In actual breeding experiments, in- 

 volving the statistically rather small numbers which experiments 

 with higher vertebrates must always be contented with, it would 

 be very difficult to distinguish critically between such condi- 

 tions as those represented in figures 5 and 6 respectively. It 

 may be the case that figure 6 represents the conditions with 

 Stockard's guinea pigs actually more truly than does figure 5. 

 It would need larger numbers of animals and more detailed 



