. The ecology and life history of the common frog (Rana temporaria temporaria). Rana temporaria. THE BREEDING BEHAVIOUR OF THE FROG 169 ill-defined scrambling movements, and 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 ecology and life history of the common frog (Rana temporaria temporaria). Rana temporaria. THE BREEDING BEHAVIOUR OF THE FROG 169 ill-defined scrambling movements, and 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 and at , 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—() 24 Please note that thes
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