68 ANALOGY BETWEEN ANIMAL 



of animals and vegetables ; yet these matters nourish 

 neither the animal nor the vegetable, until they have un- 

 dergone certain preparatory processes, and are reduced 

 to a soluble state. Solid substances, so long as they 

 remain sohd, can benefit neither the animal nor the vege- 

 table. 



The stomach is the place where these preparatory 

 processes are performed for the animal — the soil is the 

 place where they are carried on for the vegetable ; — 

 where the food undergoes the first process of decomposi- 

 tion, is broken down and rendered solvent, by the gastric 

 juices of the stomach, and the moisture and constituents 

 of the soil. 



After this process is completed, the nutrient matter of 

 the animal food is taken up by the lacteals of the animal, 

 and sent to the lungs, for its final preparation to become 

 flesh, bone, &c. — and the nutrient matter of the vegetable 

 is taken up by the spongioles, or the extreme points of 

 the minute root-fibres, and sent to the leaves for final 

 elaboration, fitted to nourish and enlarge all parts of the 

 vegetable system, and to become grain, grass, roots, &c. 



Leaves are to plants, what lungs are to animals, — the 

 organs of respiration. 



The air which is inhaled by the animal in breathing, 

 undergoes a material change ; a portion of its oxygen is 

 imparted to the blood, with which it comes in contact 

 in the lungs, and a portion of the carbon is given off by 

 the blood in exchange. By this operation the blood is 

 fitted to become hving animal matter. The leaves, in 

 like manner, are the organs of final elaboration to the 

 vegetable blood, or sap. In these, the sap is exposed to 

 atmospheric influence ; and it parts with oxygen, and 

 retains and imbibes carbon, the principal element in 

 vegetable structure, and is thus fitted to become living 

 vegetable matter. 



The animal cannot grow, nor long continue to live, 

 without the aid of the lungs. The vegetable cannot grow 

 without the aid of the leaves, nor continue to live if 

 wholly divested of them during the season of growth. 



Heat, air, and moisture are essential in all the processes 



