LECTURE VII. s 



in the lungs, without any necessity of renewal, 

 that the common Frog has been known to survive 

 six or seven days when confined by a weight at a 

 considerable depth under water*. 



Many of the amphibious animals are capable 

 of supporting a long continued abstinence from 

 food : this is particularly the case in the Serpent 

 tribe and in some of the Lizards j and so tena- 

 cious are they of the principle of life, that the 

 heart in many of the tribe will continue its pulsa- 

 tions for a long time after being taken from the 

 body ; nay, even when it has apparently ceased 

 to beat, it may again be stimulated into exertion 

 by the application of any sharp-pointed body or 

 other irritating substance. 



All the Amphibia are oviparous ; some of them 

 depositing hard eggs, or covered with a calcarious 

 shell as in birds, while others deposit soft eggs, or 

 spawn, either in the form of continued strings or 

 chains of eggs, or else in heaps or loose clusters. 

 In several of the Amphibia however, the eggs are 

 hatched internally, as in the Viper tribe and in 



* It also lies concealed during the winter season, in a state of tor- 

 pidity beneath the mud of ponds and lakes. 



