306 POPULAR HISTORY OF THE AQUARIUM. 



would go far towards exterminating the ruthless enemies to 

 utilitarian gardening. 



In watching the development of the young Tadpole into 

 the more perfect animal, it is observed that as soon as the 

 gills have attained their greatest development, they begin to 

 diminish in size, and are gradually reduced so as to be 

 contained within a cavity and enclosed by a kind of valve 

 in the skin. The eyes being perfectly formed and the lips 

 becoming movable, the Tadpole begins to be active in 

 securing food, which in this state is of a vegetable nature. 

 The fin-like web on the tail becomes much enlarged, to fit 

 it for rapid motion in search of food. By degrees little 

 tubercles at the sides of the body successively announce a 

 commencement in the production first of the hinder and 

 then of the fore limbs. In proportion as the hinder legs 

 become developed, the tail-fin wears away, and then the tail 

 itself becomes gradually absorbed, till, " small by degrees 

 and beautifully less,^^ it is finally lost altogether, and the 

 animal uses his hind legs with webbed feet for progression 

 through the water, until, emerging from that element, he 

 uses them for leaping on land. Now, no longer a vegetable- 

 eating Tadpole, he is an air-breathing Frog, feeding on in- 

 sects and worms. For the latter change the young Tadpoles 



