INFLUENCE OF THE FOOD ON THE PRODUCE. 133 



It will be evident from the preceding considera- 

 tions, that the products generated by a plant may 

 vary exceedingly, according to the substances given 

 it as food. A superabundance of carbon in the 

 state of carbonic acid conveyed through the roots 

 of plants, without being accompanied by nitrogen, 

 cannot be converted either into gluten, albumen, 

 wood, or any other component part of an organ ; 

 but either it will be separated in the form of excre- 

 ments, such as sugar, starch, oil, wax, resin, man- 

 nite or gum, or these substances will be deposited 

 in greater or less quantity in the wide cells and 

 vessels. 



The quantity of gluten, vegetable albumen, and 

 mucilage, will augment when plants are supplied 

 with an excess of food containing nitrogen ; and 

 ammoniacal salts will remain in the sap, when, for 

 example, in the culture of the beet, we manure the 

 soil with a highly nitrogenous substance, or when 

 we suppress the functions of the leaves, by removing 

 them from the plant. 



We know that the ananas is scarcely eatable 

 in its wild state, and that it shoots forth a great 

 quantity of leaves, when treated with rich animal 

 manure, without the fruit on that account acquiring 

 a large amount of sugar ; that the quantity of starch 

 in potatoes increases, when the soil contains much 

 humus, but decreases when the soil is manured 

 with strong animal manure, although then the 

 number of cells increases, the potatoes acquiring 



