1 82 AMPHIBIA 



case, as in a human being, the evaporation from the frog's 

 moist skin keeps its body temperature below a certain limit, but 

 many species with drier skins, such as the toads, habitually avoid 

 the sunshine, and conceal themselves in the daytime in holes or 

 under stones, and many of them in somewhat dry, hot climates 

 activate in a torpid condition like the Dipnoi among fishes. 



In Central Australia, according to the description of Pro- 

 fessor Baldwin Spencer, Chiroleptes platycephalus was found in 

 the dry season about a foot from the surface in a "clay-pan," 

 i.e. a depression of the ground covered with clay which would 

 be the bottom of a shallow pond in the wet season. The body 

 was distended into a spherical shape and completely filled the 

 cavity which it occupied. This distension was due to the water 

 which the body contained, some in the urinary bladder, some 

 in the subcutaneous spaces, but the greater portion in the body 

 cavity itself. 



In temperate climates, on the other hand, Amphibia become 

 torpid in winter, in which condition they cease to breathe air and 

 depend on cutaneous respiration. In this state they can endure 

 any degree of cold provided the internal organs are not com- 

 pletely frozen so that the tissues are killed ; the circulation is 

 suspended and the heart ceases to beat, but when the tempera- 

 ture rises again it resumes its functions and the animal becomes 

 as active as before. Frogs and other Amphibia often hibernate 

 in the mud at the bottom of ponds, the pulmonary respiration 

 being suspended when they are in this condition, whereas in 

 summer they would soon be drowned if kept for an indefinite 

 time under water. 



