FEEDING 
combined they form definite substances with definite propor- 
tions entirely independent of the original elements. The pure 
diamond is carbon. Gasoline is carbon and hydrogen. Several 
hundred other things are also carbon and hydrogen. Sugar is 
carbon combined with hydrogen and oxygen. These three ele- 
ments make several thousand different substances, including 
fats, alcohol and formaldehyde. Hydrocyanic acid is carbon 
combined with hydrogen and nitrogen, and is the most deadly 
poison known. : 
The failure of food science is partly because we do not 
know the composition of many of the substances of food and 
partly because these substances are changed in the animal 
body a a manner which we do not understand and cannot 
control. 
Conventional Food Chemistry. 
The conventional analysis of feeding stuff divides the food 
substances in water, carbohydrates, fat, protein and ash. The 
amount of water in the body is all-important, but, with the 
exception of eggs during incubation, I confess I prefer to rely 
upon the chicken’s judgment as to the amount required. 
The carbohydrate group contains starch, sugar, cellulose and 
a number of other things. Carbohydrates constitute two-thirds 
to three-fourths of all common rations and nine-tenths of that 
amount is starch. The proposition of how much carbohydrates 
the hen eats is chiefly determined by the quantity of grain she 
consumes. 
Of fats there are many kinds of which the composition is 
definitely known. The amount of fats the hen eats is unim- 
portant because she makes starch into fat. The protein or 
nitrogen containing substances of the diet is the group of 
food substances over which most of the theories are expound- 
ed. The hen can make egg fat from corn starch or cabbage 
leaves because they contain the same elements. She cannot 
make egg white from starch or fat because the element of 
ei which is in the egg white is lacking in the starch 
and fats. 
The substances that have nitrogen in them are called pro- 
tein. They are very complex and difficult to analyze. In 
digestion these proteins are all torn to pieces and built up 
into other kinds of protein. Just as in tearing down an old 
house, only a portion of the material can be used in a new 
house, so it is with protein and laboratory analysis cannot tell 
us how much of the old house can be utilized in building the 
new one. 
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