342 . HAROLD CUMMINS 



were touched. Apparently, then, the recognition is based upon 

 the reaction of males. The reaction which establishes recogni- 

 tion is a combination of vocal remonstrance and struggling 

 which stimulates the clasping male through tactual (and kines- 

 thetic ?) sensations. Again, according to Yerkes ('05), sounds 

 reinforce tactual stimuli and result in motor responses, and the 

 sense of hearing serves as a warning sense to modify reactions to 

 other stimuli. 



SUMMARY 



1. By means of a trap nearly enclosing a pond, frogs of four 

 species (Rana pipiens, R. cantabrigensis, Chorophilus nigritus, 

 Hyla pickeringii) were caught as they attempted to enter the 

 pond for breeding. 



2. It was found that migration occurred in waves, during 

 periods of high relative humidity coincident with temperature 

 ranging between about 41° and 52° F. 



3. By continuous short-period day and night records of the 

 croaking of frogs in the pond it was found that intense migration 

 followed periods during which there was no croaking in the pond 

 or about it and that great vocal activity was not followed or 

 accompanied by increased migration. It is concluded that voice 

 does not direct the movement of the frogs into the pond. 



4. Observations in the open and numerous experiments on 

 frogs in terraria lead to the conclusion that sight plays no role in 

 the attempt of the male to clasp the female except to inform him 

 that there is something to be clasped. Sight was not found to be 

 essential for correct coupling and is believed to play no role in sex 

 recognition. 



5. Males were found to clasp other males as well as females. 

 Clasped normal males struggle, inflate the vocal sacs and croak, 

 and are always released. Clasped females show usually brief 

 and weak resistance and the clasp is nearly always retained. 

 Sex Recognition^ as manifested in normal pairing thus results fro7n 

 the differential behavior of the tivo sexes when clasped, and depends 

 X)n the reaction of the clasping male toward this differential behavior. 



