28 Elementary Principles of Food. 



Chyle passes through the lacteals from the in- 

 testines. Its constituents gradually form a 

 granular-looking mass, in which float a number 

 of small vesicles or cells. By passage through 

 an assemblage of bodies called mesenteric glands, 

 the cells increase in number, and at length ac- 

 quire colour, and eventually are poured into 

 blood vessels near the heart. It is thus the blood 

 becomes the pabulum whence all tissues are 

 nourished. In the elements of food are found 

 the materials which, after assimilation, partake of 

 the characters of the tissues of the body ; and the 

 circulation of the blood explains how each kind 

 receives its share. 



ELEMENTARY PRINCIPLES OF FOOD. 



The chyle contains the whole of the elements 

 of the food. These are of a mixed character. 

 First, we have nitrogenous, so-called because they 

 contain largely the gas nitrogen, or albuminous 

 principles which are strictly the elements from 

 which muscle is developed hence the term 

 " flesh formers " which is applied to them. 

 Second, we have fatty bodies and saccharine or 

 sugary principles starch, gum, sugar, &c. heat- 

 producers. Third, there are essential constituents 

 in the form of salts of lime, potash, soda, mag- 

 nesia, Sec. Fourth, various acids, as hydro- 

 chloric (muriatic acid or spirits of salt), nitric 



