MATING BEHAVIOR OF THE WOOD FROG. l8l 



Experiment 14. A dark female, with eggs, was paired with 

 readily though my impression was that it was not so eagerly 

 pursued and seized as the reddish brown ones. 



Experiment 19. Thinking a chemical sense perhaps involved 

 in sex-recognition, tried a male with the contents of the cloaca 

 and uterus of a female smeared over the posterior portion of his 

 body. There were no more reactions than common to a male 

 though I tried several times and with the cloacal parts of two 

 females, one of which was the reddish brown one (Exp. 9) which 

 had seemed particularly attractive to the males and with which 

 so many males had been captured. The male probably did not 

 retain the material on his body long when moved in the water. 

 Several times however the decoy was gotten near a male before 

 there had been much chance for the material to become washed 

 off. 



From these and other experiments it was made clear that the 

 females alive or dead with or without eggs were recognized by the 

 males though the dark ones without eggs were not so eagerly 

 seized as the reddish brown ones and the dark ones still with the 

 eggs were probably less readily recognized than the brown ones. 



As regards sex-recognition the behavior of these frogs may be 

 stated as follows. The males test every frog or moving object 

 within a radius of several feet. As compared with the male the 

 different behavior of the female in the pond probably serves as a 

 partial means of sex-recognition. One gains the impression that 

 he can distinguish a female in the pond as far as she is readily 

 visible, for the female swims with long gliding strokes mostly 

 under water, usually comes to the surface only momentarily 

 and dodges under on the approach of another frog; while the 

 males swim at the surface, swim about with short ineffective 

 strokes and commonly make little effort to avoid an approaching 

 frog. On the other hand occasionally a female swims at the 

 surface with movements apparently indistinguishable from those 

 of a male and on at least two occasions such females were pur- 

 sued with remarkable persistence by one or more males. It is 

 to be noted in this connection also that a rapidly swimming or 

 persistently swimming male or the struggles of more than one 



