LECTURE VH. 
& 
in the lungs, witlunit any necessity of renewal, 
that the common Frog has been known to survive 
six or seven days when confined by a w^eight at a 
considerable depth under Wter^. 
Many of the amphibious animals are capable 
of supporting a long continued abstinence from 
food: this is particularly the case in the Serpent 
r 
tribe and in some of the Lizards ; 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 wdien 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 m birds, while others deposit soft eggs, or 
spawn, either in the form of continued strings or 
chains of eggsp or else in heaps or loose clusters. 
In several of thw 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. 
