178 FISH-CULTURAL ASSOCIATION. 5 
protein. The materials used for food by man contain, taken all 
together, more carbo-hydrates than fats or protein. The carbo- 
hyarates have their normal place in our food and we could not 
dispense with them. They are of inferior value to the protein 
and fats, in the sense that there is much of the work of food in 
the body which they cannot do as well as the protein and fats, 
and much more which they cannot do at all. But they do work 
which the scarcer and dearer protein and fats would otherwise 
have to do, and, furthermore, they occur in such large propor- 
tions, especially in vegetable materials which make the larger 
part of the food of man, that their actual importance is very 
great. 
AMOUNTS OF NUTRIENTS REQUIRED FOR A DAY'S RATIONS. 
Numerous attempts have been made to determine how much 
of each of the three principal classes of nutrients, protein, fats, and 
carbo-hydrates, is needed for a day’s food for an individual, an 
adult or a child, at work or at rest. We know, in general, a man 
when hard at work requires more, because more is consumed in 
his body than the same man would when doing no work. But 
different men have different requirements, due to individual pe- 
culiarities, so that the best we can do is to take an average 
amount as expressing the need of an average man. By compar- 
ing the amounts of carbon, oxygen, hydrogen, and nitrogen, ac- 
tually found by experiments to be consumed by different indi- 
viduals, and also noting the amount and composition of the food 
consumed by different persons, estimates have been made of the 
quantities of the several nutrients by individuals of different 
classes under various conditions. Prof. von Voit, of the Uni- 
versity of Munich, for instance, who has made more extensive 
researches upon this subject, perhaps, than any one else, com- 
putes that a fair daily ration for a laboring man of average 
weight, at moderate work, would need to supply: 4.2 ounces of 
protein; 2 ounces of fats; and 17.6 ounces of carbo-hydrates. Of 
course he may get on with less of either one, provided he has 
more of the others. But there isa minimum below which he 
cannot go without injury, and especially he must not have too 
little protein. He may hgve more protein and less carbo-hy- 
