grows ; this splits along the back and thighs, is worked over the head 

 like the taking off of a shirt, and usually eaten by the wearer. The 

 deeper layers contain much pigment, in cells which are more or less 

 under muscular control, enabling Frogs to change their/ hue to con- 

 form to the background. 



y# / / 



Frogs are carnivorous, and in the season of activity are likely to 

 be very voracious. The terrestrial and arboreal forms feed mainly 

 on insects, worms, etc. The aquatic kinds also catch insects, but 

 subsist more on aquatic animals worms, tadpoles, small fishes, and 

 other Frogs. These are seized and slowly swallowed, often, where 

 before the remainder, perhaps still alive, has been got within the 

 mouth. 



Extremes of cold or drought in climate must be avoided by 

 Frogs. Moisture of the skin is necessary to their health, and in very 

 dry places or seasons they survive only by going deeply under 

 ground. Thus some tropical species get through the "dry season." 

 The frogs of northern climates endure the winter by clustering 

 about spring-holes and other places where the water is comparatively 

 warm and free of ice ; or else by hibernating in the mud. Terrestrial 

 species bury themselves for the winter in the loam, or burrow into the 

 dry dust of rotting logs and stumps. Their vitality is strong, and 

 their power of regeneration from partial congelation is very great. 



Though most species live always in or near water, many spend 

 the greater part of their time away from it, and often in bushes or 

 trees. These, however, go to the water to breed ; and as this function 

 is likely to demand attention early in the spring, it is then that these 

 animals make themselves most conspicuous by the incessantly ut- 

 tered croaking or rattling calls of the males, which are almost as 



16 



