CHEMICAL COMPOSITION OF PLANTS. 



125 



the form of ash. The relative proportion of these constituents varies 

 in different species, as seen in the following table by Solly, in which 

 the proportions are given in 10,000 parts of the fresh plants : — 



The following table, by Johnston, represents the constituents in 

 1000 parts of plants and seeds, dried at 230° Fahrenheit, and in the 

 state in which they are given to cattle ; the organic matter being 

 indicated by the carbon, oxygen, hydrogen, and nitrogen ; the inorganic 

 by the ash : — 



Wheat. Oats. Peas. 



465 



61 



401 



42 



31 



By the process of drying, the 1000 parts 

 water in the following proportions : — 



Wheat 166 ... Peas 86 



Oats 151 ... Hay 158 



As plants have no power of locomotion, it follows that their food 

 must be universally distributed. The atmosphere and the soil ac- 

 cordingly contain all the materials requisite for their nutrition. These 

 materials must be supplied either in a gaseous or a liquid form, and 

 hence the necessity for the various changes which are constantly going 

 on in the soil, and which are aided by the efforts of man. Plants are 

 capable of deriving all their nourishment from the mineral kingdom. 



