THE BREEDING BEHAVIOUR OF THE FROG 



169 



ill-defined scrambling movements, and 5.55 spawning occurred clear 

 away from other frogs, on the glass bottom of the tank. It was a 

 remarkable experience. Not more than five seconds elapse between the 

 first appearance of eggs at the cloaca, and the completion of expulsion 

 of the whole mass of eggs. They are ejected forcibly, and stream over 

 the surface of the glass, rapidly at first, then more slowly, like hot 

 pitch flowing over a cold surface. The ejection of the eggs was 

 apparently aided by the hands of the female, which were pressed so 

 hard on her abdomen that depressions were visible. Possibly the greater 

 part of the propidsive power needed for this very rapid expulsion is 



Fig. 44. Rear View of a Pair of Frogs 



Note again the defensive position of the feet of the male, quite different 

 from that of the female. Note also the position of the vent of the female. 

 A stream of eggs being squirted violently out of the vent would almost 

 certainly brush past the ventral surface of the male, and this probably 

 provided the stimulus for the emission of sperm. 



provided by the muscles of the female's arms. Waring, Landgrebe 

 and Neill (1941) were puzzled to account for the propulsive force in 

 this species, and said that they searched the Hterature without fmding a 

 description of oviposition, although there are at least three. It really 

 adds interest to find that these authors had independendy realized 

 that there was something remarkable to explain, for the weak abdominal 

 muscles do not seem sufficient. The male has often been credited 

 with helping expulsion, but his arms are placed too far forward. 



Two more pairs spawned in the tank, at 6.20 and at 7.00 a.m., and 

 I was able to confirm the above observations. In one case, the female 

 clambered to the top of one of the previously laid clumps, and laid her 

 12— (T.914) 24 pp. 



