NON-NITROGENOUS NUTRIENTS. 39 



Carbon. Hydrogen. Oxygen. 



Per cent. Per cent Per cent. 



Pure cellulose 44.44 6.17 49.39 



Cellulose, mixed with lig- 



nin 55.30 5.80 38.90 



Starch 44.44 6.17 49.39 



Cane sugar 42.11 6.43 51.46 



Milk sugar 42.11 6.43 51.46 



Grape sugar 40.00 6.67 53.33 



Fruit sugar 40.00 6.67 53.33 



Gum 45.10 6.10 48.80 



Fats 76.50 12.00 11.50 



The pectine substances have a composition probably very 

 similar to gum. The above table will show, at once, how 

 close a relation there is between all the members of this 

 group of substances. The fats are not usually classed with 

 the carbo-hydrates, because the oxygen and hydrogen are 

 not in the proportion to form water, but being composed 

 of the same elements, and answering the same purpose in 

 the animal economy, they may all be classed together. 

 Even when fat is used to supply animal heat it has two and 

 one-half times the heating power of starch. 



In all plants cultivated for food, there is a greater or less 

 amount of fatty matter, identical in composition with the 

 several kinds of fat in animal bodies. The fatty matters 

 of the food are extracted by the stomach of the animal, 

 and easily assimilated. Plants prepare fatty matters from 

 their elements carbon, oxygen and hydrogen and present 

 them ready-formed to the animal. But the animal pos- 

 sesses the power of preparing fat from starchy food when 

 there is not fat enough ready-formed for its wants, and may 

 accumulate fat from starchy food, when given in abundance. 



INORGANIC NUTRIENTS. 



Our food plants also receive from the soil phosphates of 

 lime, magnesia, and soda, chlorides of sodium and potas- 

 sium, oxide of iron, sulphate of iron, and potash ; and 

 these same compounds exist in the bodies of animals in the 



