INFLUENCE OF THE FOOD ON THE PRODUCE. 137 



acid; and their consequent adaptation for entering 

 into the composition of the diiferent organs. 



The carbon abstracted from the carbonic acid 

 acquires in the leaves a new form, in which it is 

 soluble and transferable to all parts of the plant. 

 In this new form the carbon aids in constituting 

 several new products ; these are named sugar when 

 they possess a sweet taste, gum or mucilage when 

 tasteless, and excrementitious matters when ex- 

 pelled by the roots. 



Hence it is evident, that the quantity and quality 

 of the substances generated by the vital processes 

 of a plant will vary according to the proportion 

 of the diiferent kinds of food with which it is 

 supplied. The development of every part of a 

 plant in a free and uncultivated state depends on 

 the amount and nature of the food aiforded to it, by 

 the spot on which it grows. A plant is developed 

 on the most sterile and unfruitful soil, as well as on 

 the most luxuriant and fertile, the only difference 

 which can be observed being in its height and size, 

 in the number of its twigs, branches, leaves, blos- 

 soms, and fruit. Whilst the individual organs of a 

 plant increase on a fertile soil, they diminish on 

 another, where those substances which are neces- 

 sary for their formation are not so bountifully 

 supplied ; and the proportion of the constituents, 

 which contain nitrogen, and of those which do not, 

 in plants varies with the amount of nitrogenous 

 matters in their food. 



