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Journal New York Entomological Society. [Vol. xxiii, 



acter and incidence of parasites. Thus suppose that the factor which 

 determined the dififerences in the frequency of parasitization of pods 

 of different classes were number of ovules formed per pod, and that 

 the number of seeds developing had no independent influence in de- 

 termining whether a seed should or should not be parasitized. Never- 

 theless on tabulating his data according to number of seeds per pod 

 one would actually find the percentage frequency of parasitism to 

 some extent dependent upon, or modified by, the number of seeds 

 matured per pod, for the simple reason that the number of seeds 

 matured is within limits determined by the number of ovules orig- 

 inally laid down. 



The problem of differentiating these two factors is in the present 

 case one of some complexity, and demands for its final solution fur- 

 ther observations of various kinds. 



One may make some progress by a two-fold classification of the 

 data already in hand. By sorting the records for the individual 



Diagram 5. Relationship between number of seeds matured per pod and 

 percentage frequency of Bruchus for pods with various numbers of ovules. 

 Golden Wax beans. 



