LECTURE VII. 
23 
groupes or clustered masses ; each egg being of 
a gelatinous substance, perfectly transparent, and 
containing the young animal in its centre under 
the form of a round black globule. In the space 
of about a month the globule assumes an oval 
shape, and soon after hatches ; not in the form of 
a complete Frog but of what is termed a tad- 
pole, and appearing, on a general view, to con- 
sist merely of head and. tail; the former black 
and large, the latter slender, and bordered with 
a transparent finny margin. The motions of the 
tadpoles are very lively, and in the advanced state 
of Spring are so plentiful that the waters they 
inhabit appear blackened by their numbers. They 
live: on the leaves of the plant called duckweed 
and on other small vegetable substances: during 
the early part of their growth they are furnished 
on each side the head with a pair of ramified 
breathing organs, which drop off when they are 
farther advanced in age; and when they have 
arrived at the age of five or six weeks, the hind- 
legs make their appearance, and soon afterwards 
the fore-legs. Some time after this the tail begins 
to decrease, and at length becomes quite obli- 
terated. The animal now ventures upon land. 
