80 CHEMISTRY, GEOLOGY 



air taken into the lungs, and forms carbonic acid 

 gas. 



Gluten must form a part of the food of animals, 

 for the purpose of supplying to the muscles, or 

 lean part of the body, new substance to make 

 good their daily loss. Every portion of the 

 body is, by a similar change of atoms, constantly 

 being formed anew ; and, as the daily added por- 

 tions have fulfilled their purpose in the struc- 

 ture and uses of the several organs and their 

 adaptations, they are again, in the form of 

 excrementitious matter (sweat, urine, dung, 

 carbonic acid gas, etc.), thrown off as waste. 



Gluten supplies the waste of muscles, because 

 the gluten of plants and the muscles of animals 

 are chemically identical ; that is, they contain 

 the same elements. If an animal eats more 

 gluten in its food than is required to supply mus- 

 cular waste, the excess thereof is transformed 

 into fat. 



Food which contains the most fatty matter 

 will fatten an animal in less time than those 



Questions. Why must gluten be contained in the food 

 of animals? Why does gluten supply muscular waste? 

 What becomes of any excess of gluten contained in the food ? 

 What kind of food will most quickly fatten an animal ? 



