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THE AMERICAN NATURALIST [Vol. LI 



were obviously alive when the mother was killed. As 

 the females were killed by chloroforming, all embryos 

 were usually dead by the time they were examined. The 

 following tables give the results obtained. Each of the 

 first four tables represents one of the four types of mat- 

 ings described above. In a few instances there has been 

 some uncertainty as to the exact stage of gestation at 

 which the embryos were removed, but in such cases this 

 has been determined approximately by means of weights 

 of the living embryos. 



TABLE I 



Yellow ? x Yellow ^ 



Ybxlow $ X NON--S 



The data presented agree in the main with Kirkham's, 

 but our percentage of dead embryos A, from the yellow 

 X yellow mating (Table I) is considerably less than his, 

 while our percentage from the non-yellow X non-yellow 



