THE ALLIES OF THE FROG 345 



places, under logs and stones. They do not even go to the 

 water to lay their eggs but deposit them among moist leaves 

 and in rotten wood. Salamanders and newts hatch as tad- 

 poles, which develop into the adult form without a strongly 

 marked metamorphosis. The young of most species may be 

 distinguished from the tadpoles of the toad, and from those 

 of our various species of frogs, by their more elongate form. 

 The gills are usually visible externally for a longer period 

 than is the case with the toad and the frogs. Some species 

 retain their gills throughout life, though the lungs are also 

 functional ; in others, though the gills are absorbed in adult 

 life, the gill openings are retained ; in still others all traces 

 of gills and gill slits disappear; and, finally, a few species 

 lose their lungs also, when mature, depending entirely upon 

 the skin for respiration. 



The genus Ambys'toma includes some of the largest of our 

 species, known by the common name of blunt-nosed sala- 

 manders. The color is black, spotted with yellow. As these 

 salamanders are protected by an acrid secretion from the 

 mucous glands of the skin, the conspicuous colors are pos- 

 sibly to be interpreted as warning coloration. The adults 

 live in damp places and lay eggs in the water in large masses 

 resembling frogs' eggs, though the jelly-like mass which sur- 

 rounds them is more opaque. The young keep their gills 

 for a considerable period, and one species (Ambystoma 

 tigri'num) may even breed in the gill-bearing larval stage. 

 These immature forms, called the axolotl, live in the 

 water, growing to be eight or nine inches long, or, in excep- 

 tional cases, even larger, and may continue in this condi- 

 tion for years, without ever changing to the adult form. 



Like some other amphibians these salamanders can regen- 

 erate lost limbs. This, according to Professor Gadow of 

 Cambridge, England, takes place more certainly and quickly 

 the younger the animal is. In one case quoted by this 



