136 ON THE FOOD OF PLANTS. 



exertion of those powers ; or any improper sub- 

 stance being taken into the system with the 

 food ; must be followed by disorder, disease, and 

 destruction. 



One great power which plants are allowed 

 to possess, and which seems absolutely neces- 

 sary ; is the decomposition of water, and the 

 emission of oxygene ; for, from the proportion 

 of oxygene in water, being so much greater than 

 in any of the vegetable products, the plant must 

 take up more than it can need ; and the great 

 power and activity of oxygen is such, that un- 

 less plants had the means of expelling the super- 

 fluous quantity, they could not exist, nor could 

 the different products be formed. But plants do 

 not appear to possess the power of expelling hy- 

 drogene ; therefore, whatever quantity of this 

 substance be taken into the system, it must re- 

 main and be appropriated. With these ideas, the 

 following analysis will be found generally to ac- 

 cord: 



Water contains, 85 parts oxygene, 



15 - hydrogene. 



Oil contains, 79 parts carbon, 



21 - hydrogene. 



Sugar contains, - 28 parts carbon, 



8 - hydrogene, 



64 v oxygene. 



