ITS SOURCE, THE ATMOSPHERE. 21 



firms the view, that the elements of water are assi- 

 milated at the same time. 



The life of plants is closely connected with that 

 of animals, in a most simple manner, and for a wise 

 and sublime purpose. 



The presence of a rich and luxuriant vegetation 

 may be conceived without the concurrence of 

 animal life, but the existence of animals is un- 

 doubtedly dependent upon the life and develop- 

 ment of plants. 



Plants not only afford the means of nutrition for 

 the growth and continuance of animal organization, 

 but they likewise furnish that which is essential for 

 the support of the important vital process of respira- 

 tion ; for besides separating all noxious matters 

 from the atmosphere, they are an inexhaustible 

 source of pure oxygen, which supplies the loss 

 which the air is constantly sustaining. Animals 

 on the other hand expire carbon, which plants in- 

 spire ; and thus the composition of the medium 

 in which both exist, namely, the atmosphere, is 

 maintained constantly unchanged. 



It may be asked, Is the quantity of carbonic 

 acid in the atmosphere, which scarcely amounts to 

 l-10th per cent., sufficient for the wants of the 

 whole vegetation on the surface of the earth, is 

 it possible that the carbon of plants has its origin 

 from the air alone ? This question is very easily 

 answered. It is known, that a column of air of 

 2216.66 Ibs. weight, Hessian measure, rests upon 



