From the results of numerous experiments under normal activity, the quantity of nitrogenous food estimated to maintain the best bodily condition is about three-fourths of a decigram for each pound of body-weight; less than one-half of a decigram per pound of body-weight would cause nitrogen starvation, while more than one decigram per pound, except in the cases just mentioned, would result only in thrusting needless work upon the liver and the kidneys, whose duties are to guard the body against the results of incorrect eating. There are certain conditions under which this amount of nitrogen may be exceeded in order to gain definite and specific purposes, but in such cases the nature of the proteid is of great importance. In certain occupations, for instance sedative labor, the most soluble proteids, such as egg albumin (white of eggs), milk, and green peas and beans should be selected; while in cases of heavy manual labor, the heavier proteids, such as nuts, cheese, dried legumes, fish and fowl should be selected. LESSON VII FOODS OF ANIMAL ORIGIN An intelligent discussion of this lesson leads us directly into a subject commonly known as "vegetarianism." The question whether man should eat the flesh of animals is especially fascinating for those who give attention to the food they eat. There are many standpoints, however, from which the subject of vegetarianism may be discussed. [Sidenote: Influence of religion on man's food] In the first place, nearly all religious teachings that have wielded such a powerful influence over the civilization and destiny of men, have laid some restrictions upon the flesh-eating habit. Some religions require man to refrain from all animal products, while others interdict only the flesh of certain animals. Coupled with man's world-wide search for food, these religious teachings have played a conspicuous part in the question of human nutrition. [Sidenote: Vegetarianism from animal's standpoint] The second phase of the question that merits attention is the moral side, or vegetarianism from the animal's standpoint; in other words, the cruelty involved in the slaughter of our dumb friends and helpers, for whose presence here we are largely responsible. That the practises and customs which train humanity in cruelty toward animal life, are to be discouraged, cannot well be disputed, but this phase of vegetarianism is one which is somewhat without the realm of applied food chemistry, hence is mentioned only as a factor in the general discussion. [Sidenote: Vegetarianism from standpoint of scientific living]