176 FISH-CULTURAL ASSOCIATION. 
ine forms sodium chloride, common salt. Calcium with phos- 
phoric acid forms calcium phosphate or phosphate of lime, the 
mineral basis of bones. 
Our bodies contain scores of compounds, many of which can 
not be included in either of the-above four classes. But the 
bulk of the compounds in the bodies of animals, as well as in 
the food by which they are nourished, are either water or some 
material which we may call protein, fats, carbo-hydrates, or 
mineral matters. 
Animal foods, as meats, fish, etc., contain but little of carbo- 
hydrates, their chief nutrients being protein and fats. Milk, 
however, and some shell fish, as oysters, scallops, etc., contain 
more or less of carbo-hydrates. Vegetable foods, as wheat, po- 
tatoes, etc., contain less protein and consist largely of starch, 
sugar, cellulose, and other carbo-hydrates, though nearly all 
contain more or less of fats. 
THE FUNCTIONS OF THE NUTRIENTS. 
These different nutrients as we have seen, have different offices 
in nourishing the body, in building up its tissues, repairing its 
wastes, and serving as fuel to produce animal heat, and muscu- 
lar and intellectual energy. Just what is done by each class, 
exactly how they are transformed and used in the body, is not 
yet fully known. Still we have to-day a tolerably fair idea of 
the principal parts played by each class of nutrients. 
According to views formerly held and frequently met with, 
still, the protein compounds were regarded as the “ flesh-form- 
ers’? and the sources of muscular energy, while the carbo- 
hydrates and fat were looked upon as “fat-formers” and “ heat- 
producers.” A vast deal of painstaking research, however, has 
shown that these distinctions were not correctly drawn. The 
albuminoids are flesh-formers, it is true; indeed, according to 
the nearly unanimous testimony of the most trustworthy experi- 
ments, flesh, z. ¢., muscular and other nitrogenous tissue, is made 
from the nitrogenous constituents of the food exclusively. But 
the balance of testimony is decidedly against the production of 
muscular energy exclusively or mainly, by nitrogenous com- 
