THE CHEMICAL ELEMENTS 



21 



Carbon constitutes a larger proportion than any other 

 element of the dry substance of plants of all species. 

 Oxygen stands next in order, followed by hydrogen and 

 then nitrogen. It is an important fact in the economy of 

 nature that those elements which, on the average, make 

 up 93.5 per cent of the dry matter of plants have as their 

 main source either the atmosphere or water. Only a 

 small percentage of the dry matter is drawn from the 

 soil, and it is this small part that sustains the most impor- 

 tant economic relations to the farmer's business. 



25. Elements in plant ash. The elements of the ash 

 vary materially in relative quantity in different plants. 

 The following table gives the proportion of the ash ele- 

 ments in a number of agricultural products: 



TABLE II 

 ASH ELEMENTS IN CEREAL GRAINS AND VEGETABLES* 



* Calculated from Wolff's "Aschen Analysen." It is realized that more modern 

 methods of analysis might modify the above figures to a small extent, but they 

 are sufficiently accurate for illustration of the variable composition of the ash of 

 different species. 



26. Elements in animals. The proportions of the 

 chemical elements of our larger animals have been deter- 



