416 



THE UNIVERSE. 



disoi-ders called forth bj the animal kmgdom; each lAimt 

 represents a regular mac/iiue fo>' pur>/f/tii(/ the air. 



227. Kespiration of Plants. Diseng.igement of Oxygen \inder Water. 



Plants require a large quantity of carbon for their 

 nourishment and the formation of their solid framework. 

 For this purpose they absorb all the carbonic acid they 

 can find in the air, and then fix its carbon in their tissues 

 Ijy exhaling the oxygen; a twofold action, in the comse 

 of which they render the air Avholesome, and regenerate 

 it by restoring the vital gas which animals alisoi'b, and re- 

 moving the poison Avhich they continually diffuse. 



This harmonious contrast will strike every one, and Ave 

 see that it is destined to counteract the incessant changes 

 which the animal kingdom introduces into the atmosphere, 

 and to protect it from all serious perturbation. According 



