THE FROG. 
229 
fiom each other, may be necessary. The frog moves by leap- 
ing • the toad crawls along the ground : the frog is in general 
less than the toad ; its colour is brighter, and with a more po- 
lished surface : the toad is brown, rough, and dusty. The 
hog is light and active, and its belly comparatively small- the 
toad is slow, swollen, and incapable of escaping^ Thefroo- 
when taken, contracts itself so as to have a lump on its back’ 
the toad’s back is straight and even. Their habitudes and 
manners exhibit a greater variety, and require a separate 
description. 
The external figure of the frog is too well known to 
need a description. Its power of taking laro-e leaps is re- 
markably great, compared to the bulk of its body • and it 
is the best swimmer of all four-footed animals. 
If we examine this animal internally, we shall find that it 
has very little brain for its size ; a very wide swallow- a 
stomach seemingly small, but capable of great distension. 
A he heart in the frog, as in all other animals that are truly 
amphibious, has but one ventricle ; so that the blood can 
circulate without the assistance of the lungs while it keeps 
hnder water. The lungs resemble a number of small blad- 
ders joined together, like the cells of a honey-comb : they 
are connected to the back by muscles, and can be distended 
or exhausted at the animal’s pleasure. Neither male nor 
remale have any of the external instruments of generation • 
the anus serving for that purpose in both. Such are the 
?nost striking peculiarities in the anatomy of a fro<x- and 
'n these ‘t agrees with the toad, the lizard, and the serpent. 
I he female is impregnated neither by the mouth, as some 
Philosophers imagine, nor by the excrescence at the thumbs, 
!? was the opinion of Linnaeus; but by the dispersion of 
ihT [ H ' E ” esem * na ^ upon the eggs as they proceed from 
A single female produces from six to eleven hundred 
8gs at a time ; and, in general, she throws them all out 
°getner by a single effort ; though sometimes she is an 
n °ur in performing this task. 
When the spawn is emitted and impregnated by the male 
drops to the bottom. The eggs, which during the four first 
ours suffer no perceptible change, begin then to enlarge and 
fi' w i'gnter: by which means they mount to the surface of 
e water. The twenty-first day the egg is seen to open a 
whi^i°i* ° ne sic * e ’ ar *fl A ie beginning of a tail to peep out, 
(V ■ c 1 bgcomes a more and more distinct every day. The 
"ty-nintb day the little animal begins to have motion; it 
ves at intervals its tail ; and it is perceived that the 
