THE BREEDING BEHAVIOUR OF THE FROG I73 



his feet at her cloaca, no eggs emerge, the male immediately loses his 

 hold and swims away. If a female that has fmished spawning is again 

 seized by a male, she has only to go through these motions again to 

 dismiss liim. It is a remarkable sight — the vigorous little male acts as 

 if he is under a spell. In Bomhina variegata the female makes herself as 

 thin as possible, and crawls, mewing plaintively. Tliis casts a spell 

 on the male, who relaxes his grip. Gingerly, mewing all the time, the 

 female crawls out of his arms, appearing to take care not to touch the 

 male and so stimulate him to grip her again. It is a delicate operation, 

 and may not succeed the first time, but as in the other species, I do not 

 believe that she is ever retained for long if she wants to get away. All 

 she has to do is to administer the dismissal stimulus. 



To conclude this account of the dismissal stimulus in R. temporaria^ 

 the female is capable of using her voice before she has laid her eggs. 

 The only pair that did not spawn during my successful night of obser- 

 vations was left in the tank, now filled with tap water. After some 

 days, the frogs were found to have separated, and the female, although 

 still full of eggs, grunted and dodged away when touched or seized 

 by the male. Not much importance can be attached to the fact that 

 he did not retain her, for he was by this time probably somewhat 

 exhausted, but the observation seems to show that some change 

 occurred in the female that caused rejection of the male by the use of 

 the dismissal stimulus. Her silence during normal breeding is not due 

 to mechanical inability to croak, because she is too full of eggs, but to 

 the fact that she is then ready to accept the male. In fact, throughout 

 the season, in all three species, it is the female that is really in charge of 

 the events. It is she that swims to the spawning site, chooses the time 

 and place for laying the eggs, and departs when her task is done. 



Noble and Farris (1929), Noble and Aronson (1942), and Aronson 

 (1944), have contributed important observations of the sexual behaviour 

 of American frogs and toads. In reading their work, I am struck both 

 by the resemblances and the differences from that of R. temporaria. 

 Noble and Farris's paper is particularly interesting, because the frog 

 they studied was the American Wood Frog, R. sylvatica, closely 

 related to R. temporaria. Anyone who compares their account with 

 those of my two predecessors and myself, must conclude that the 

 differences are, in places, more than can be accounted for by differences 

 in the observers. Sex-recognition, Noble and Farris think, is accom- 

 phshed by the males embracing other frogs regardless of sex, and 



