FROGS AND THEIR RELATIVES 



117 



adult stage cover themselves more or less with dirt in the daytime, 

 and come out at night to feed upon insects, which constitute their sole 

 food. Instead of having a smooth, slimy skin, as does the frog, 

 a toad's skin (Fig. 87) is dry and covered with elevations com- 

 monly known as " warts." These elevations contain cells which 

 secrete an irritating substance that protects the toad from animals 



FIG. 87. The toad. Note its resemblance to its surroundings, whereby 

 it is likely to be protected. 



that would prey upon it. There is no foundation, however, for 

 the popular notion that the warts of human beings are ever caused 

 either by toads or frogs. 



In springtime toads seek the water in which to breed. The eggs, 

 covered with a gelatinous substance are laid in long strings instead 

 of in masses, as was the case with frogs. The development and life 



