314 THE REASON WHY : 



" He that has humanity, forewarn'd, will tread aside, and let 

 the reptile live." COWPKR. 



1000. Why do birds moult, or change their feathers, 

 periodically ? 



The moulting of birds is a process analogous to the nutrition, 

 expenditure, and decay, which occurs in all animal bodies. When 

 an atom, or it may be an organ, has fulfilled its functions, it dies ; 

 and when completely dead, it separates and falls, because a dead 

 substance cannot co-exist with a living. 



Moulting is nothing else but this natural death of some 

 part of the bird, in consequence of the development of other 

 interior parts, which are being matured to carry on the 

 functions of the parts undergoing decay. 



1001. We find the germs of leaves, flowers, and fruits, in vegetables, and the hairs, 

 feathers, scales, horns, epidermis, &c., in animals increasing and developing them- 

 selves in spring, to flourish in succession, at least for the duration of the summer. 

 But at the approach of the autumnal equinox, plants and animals, being more or 

 less exhausted by the vast expenditure of their vital forces in the great work of 

 reproduction, and also by the increased energy with which those vital forces acted 

 in proportion to the surface, their external functions begin to be enfeebled, and by 

 so much the more as the heat of the sun diminishes. Then these external ,parts f 

 these vernal productions, cease to receive aliment through the body : they have, 

 besides, arrived at the full term of their augmentation, and can admit of no further 

 nutriment. They dry up, wither, are detached, and fall. Thus is produced, sooner 

 or- later, the fall of flowers, leaves, and fruits, and the change of hairs, feathers, 

 horns, epidermis, scales, &c. 



CLASS III REPTILIA. 



ORDER I. CHELONIA. 



1002. Why is the first order of reptiles called chelonia? 



From a Greek word meaning a tortoise ; the order including the 

 various species of tortoise and turtle. They have horny cases, are 

 destitute of teeth, have thick fleshy tongues, well developed eyes, 

 and their limbs differ from an elephantine club foot, to feet 

 divided and webbed. 



