CLASS AMPHIBIA. FROGS, TOADS, SALAMANDERS, AND OTHERS 



403 



Figure 273. Hy/d andersonii, a tree frog. (Courtesy of N.Y. Zoological Society.) 



used extensively for laboratory dissections, 

 physiologic experiments, human pregnancy 

 tests, pharmacology, and for fish bait. Mud 

 puppies {Necturus) also serve as teaching 

 material; one firm in Chicago sells 2500 or 

 more per year for this purpose. The skins 

 of frogs are used for glue and book bindings. 

 Frog legs are eagerly sought as an article 

 of food; more than three million pounds are 

 eaten every year in the United States. Mud 

 puppies are also edible. In Japan, the giant 

 salamander is much esteemed as an article 

 of food. 



Hellbenders are considered poisonous by 

 many people, but they are not dangerous to 

 man. Many superstitious beliefs are held 

 about amphibians, such as: salamanders are 

 not injured by fire, a croaking frog predicts 

 rain, and the toad has a jewel in its head. 

 In China, the skin of the toad is used as a 

 medicine; its use may have some therapeutic 

 value, since certain glands contain a digitalis- 

 like secretion which increases the blood pres- 

 sure when injected into human beings. 



Frogs and toads are widely recognized as 

 enemies of injurious insects. The toads are 

 of special value, since they live in gardens 

 where insects are most injurious. In France 

 the gardeners even buy toads to aid them in 

 keeping obnoxious insects under control. 

 Bufo marinus has been introduced in the 



tropics, especially where sugar cane is grown, 

 to control insects. 



Frog farming has been promoted for pleas- 

 ure and profit, but it has generally proved 

 a great disappointment to those who en- 

 gaged in the enterprise. Many so-called 

 "farms" are only favorable marshes where 

 natural reproduction is encouraged. Artificial 

 rearing of frogs is not practicable because it 

 is difficult to find a satisfactory supply of 

 food; unless the frogs of different sizes are 

 separated, the large ones eat the smaller indi- 

 viduals; losses from predators and disease 

 may be high where there is a great concen- 

 tration of frogs; and the selling price has 

 been inadequate to make the business profit- 

 able. Most of the money in frog farming has 

 been made by unscrupulous promoters who 

 sold breeding stock and books on frog rais- 

 ing at exorbitant prices. 



A BRIEF CLASSIFICATION 

 OF LIVING AMPHIBIA 



{For reference purposes only) 



Class Amphibia. About 2500 different spe 

 cies of living Amphibia are known, a number 

 very much smaller than that of the other prin- 

 cipal classes of vertebrates. Approximately 60 



