336 HAROLD CUMMINS 



problem is not concerned (probably associated with the state of 

 the reproductive organs, since with the exception of three imma- 

 ture frogs only sexually mature individuals migrated) govern the 

 impulse, and are operative when external circumstances become 

 favorable. Because migration is successfully accomplished 

 without the directive influence of voice, we must look elsewhere 

 for factors controlling the direction of migration. In such a 

 closely related group as the salamanders there are some forms 

 which lead a terrestrial existence at all times except during the 

 breeding season, when they resor: to water. (In the trap a num- 

 ber of examples of Ambystoma punctatum and several A. tigri- 

 num were obtained.) Here as well as in other groups which are 

 voiceless the factor of a vocal attraction is unquestionably 

 eliminated. Neither can we explain by a vocal factor the exodus 

 of frogs from their breeding places after the termination of the 

 breeding season, or the emigration of newly transformed frogs. 

 To substantiate the idea that voice is not effective, there are the 

 results of Yerkes ('05) on auditory responses in frogs. Yerkes 

 finds that while frogs possess a fairly well-developed sense of 

 hearing, its function seems to be "a warning sense which modi- 

 fies reactions to other simultaneous or succeeding stimuli." He 

 does not find evidence that it serves as an independent control of 

 motor reactions. 



SEX RECOGNITION 



The results of Holmes on Amphipods ('03), of Pearse on cray- 

 fish ('09), and of Reighard on the brook lamprey ('03) show that 

 in these animals sex recognition is established through the reac- 

 tions of those individuals with which the breeding act is attempted 

 by males. That is, there is really no precopulatory recognition, 

 rather a male may attempt union with any individual, and the 

 reactions of that individual determine whether or not the union 

 shall continue. Holt's observations on the dragonet ('98) and 

 Miss Reeves' study of Etheostoma ('07) show that behavior is 

 the criterion of recognition in these fishes. However, in these 

 instances there is a visual recognition before the onset of the 

 breeding act. Banta ('14), working on the wood frog, concludes 



