FEMALE AND MALEIIEIVIP I'l WIS. 



The three females (at the left) are growing vigorously, whiU' tlic three males (at the right), 

 under identical conditions, arc dying or already dead. Tlie difference in behavior is so 

 extreme thai Mr. Cook suggests a possible sex-limited environmental character to account 

 for it, since it seems improbable that sex alone would explain so great a difference of behavior 

 under the same conditions. (Figure 9.) 



204 



