The Recognition of Sex 229 



placed in a tube in which a small plug of loose cotton 

 was inserted a short distance from one end. The 

 males showed no tendency to enter the open mouth 

 of the tube as they might be expected to do if they 

 were attracted by the odor of the females. The ex- 

 periment of removing the organ of smell, which was 

 performed in the case of the amphipods, would be 

 a fruitless one in Cyclops, as the seat of smell is 

 located, to a considerable degree at least, in the same 

 organs that are used for clasping. 



"It is evident that mating in Cyclops is brought 

 about much as it is in the Amphipoda. The males 

 have a strong tendency to clasp other copepods; the 

 females tend to remain quiet in a condition some- 

 what resembling the death feint while being seized 

 by the males. It is not improbable that olfactory 

 stimuli may cause the males to remain with the fe- 

 male longer than they otherwise would, and they 

 may render the males more prone to seize females 

 than other males, but so far as could be deter- 

 mined by watching the behavior of the animals the 

 specific reaction of the two sexes to certain kinds 

 of contact stimuli is the main factor in bringing 

 about their association." 



In the crayfish the studies of Andrews and of 

 Pearse have shown that sex recognition is effected 

 by much the same method as is followed in the am- 

 phipods. Extracts from the bodies of females added 

 to water containing the males did not elicit the least 

 response. Nothing in the behavior of the males indi- 



