THE REASON WHY. 265 



"And my hand hath found, as a nest, the riches of the people; and as one 



gathereth eggs that are left, have [ gathered all the earth ; and there was none 



that moved the wing:, or opened the mouth, or peeped." Is AIA.H x. 



1051. Why do all bints lay eggs ? 



Because, to bear their young in any other manner, would 

 encumber the body, and materially interfere with their powers of 

 flight. 



As soon as an egg becomes large and heavy enough to be 

 cumbersome to the bird, it is removed from the body. A shell, 

 impervious to air, protects the germ of life within, until from two to 

 twenty eggs have accumulated, and then, although laid at different 

 intervals, their incubation commences together, and the young 

 birds are hatched at the same time. 



CHAPTER LIU. 



1052. Why have birds with long legs short tails ? 



Because the tails of birds are used to guide them through the 

 air, by a kind of steerage. When birds with long legs take to 

 flight, they throw their legs behind, and they then serve the same 

 purpose as a tail. 



Fig. 68. PEBCH. 

 1053. Why have fishes fins ? 



The fins of fishes are to them, what wings and tails are to birds, 

 enabling them to rise in the fluid in which they live by the reaction 

 of the motions of the fins upon its substance. 

 12' 



