The Recognition of Sex 225 



tinued my observations." 



That the male amphipods do not distinguish the 

 females by sight was shown by blacking over the eyes 

 of several males and then placing them in a dish with 

 females. It was not long before each male had 

 secured a mate. The possible role of the sense of 

 smell was tested by removing from a number of 

 males the first antennae which contain the olfactory 

 sense organs. After the specimens had recovered 

 from the slight shock of the operation they seized 

 the females and carried them about in the usual man- 

 ner. They reacted in the same way when the second 

 antennae were removed also. 



In another experiment several females were con- 

 fined within an enclosure of wire gauze which was 

 placed in a dish of water containing several eager 

 males. The males paid not the slightest attention 

 to the females within the enclosure, but after it was 

 raised and the females allowed to scatter through 

 the dish, most of the males were found carrying their 

 mates. 



"If one attentively observes Hyalellas as they are 

 swimming about, it will be seen that the males do not 

 pursue the females, great as their eagerness may be 

 to seize and carry one of the opposite sex. Only 

 when the two sexes collide in their apparently ran- 

 dom movements does the male become aware of the 

 presence of the female. When a male and a female 

 collide, the female curls up and lies quiet while the 

 male makes efforts to seize her. Should two females 



