SIDE IvIGHTS ON BIRDS 



essentially diSerent creatures from their pro- 

 genitors. The frog begins life as a fish. In 

 place of lungs, it breathes through external gills ; 

 its body is limbless, ending in a long fish-like tail, 

 with fin-like membranes with which the little 

 animal propels itself through the water. I^ater, 

 this strange being is built up before one's very 

 eye into a quadruped. It develops lungs con- 

 structed on the latest principles ; it throws aside 

 its fishy tail, projects from its person four useful 

 legs, and in its neW character proceeds to take full 

 advantage of the meadow, the sun, and the sky. 



There is one batrachian known as the axolotl 

 that holds a unique place in the animal kingdom. 

 It may be described as a child that refuses to 

 grow up. It begins in an egg, becomes a tadpole, 

 and at last, reaches the axolotl stac^e. Here 

 it goes through its Hfe-cycle : living, breeding 

 and dying. But it would appear that Nature 

 never intended it to remain an axolotl : this was 

 merely an intermediate stage : it was really de- 

 signed to grow into an amblystome, a creature 

 of higher development. Professor Dumeril, Mr. 

 Tegetmeier, and other naturalists, by reducing 

 its supply of water, forced it to abandon its youth 

 to adopt lungs for breathing and to take its proper 

 place as an amblystome. 



In the third class — ^the animals which are born 

 on the same plane as their parents, and merely 

 increase in size and power until full development 

 is attained, — ^the whole of the higher creations, 

 with man at their head, are included. ^ Yet, 

 even here, we find singular differences in the 

 relative length of childhood. For example, the 

 young of rabbits, like the young of men, are born 

 in a state of perfectly helpless babyhood, de- 

 manding at every instant maternal warmth and 

 sustenance, if they are to survive at all. The 



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