Under this heading I will consider fish and other sea-creatures.

The flesh of most fish is quite free from fat, and consists almost entirely of water and proteids. It is less concentrated than the flesh of warm-blooded animals, averaging about 18 to 20 per cent proteids, and 60 to 70 per cent water. The percentage of ash in fish is also somewhat greater than in any other flesh food. The popular idea that fish is good food for the brain originated in the fact that analysis of some fish shows a considerable percentage of phosphorus, which substance is also found in the brain. There is no reason to believe, however, that the liberal use of fish would develop or produce an excess of brain-tissue. Any well-balanced diet contains ample phosphorus to nourish the brain.

Nutrients in fish.

The true science of human nutrition lies in the knowledge of selecting, combining, and proportioning food according to age, climate, and work. When this is done, the tendency of the body is to eliminate disease and to assume normal action; this accomplished, every part of the anatomy shares in the general improvement.

My theory advanced against the use of meat because of nitrogenous decomposition products, holds true with fish, though in a somewhat limited degree. The decomposition products of cold-blooded animals are not identical with those of mammals, hence their consumption as food does not add to the percentage of human waste-products so directly as do other meats.

Fish as brain food.

Fish superior to flesh of mammals.

Oysters and clams, which are generally eaten uncooked, are recommended by many authorities as valuable sources of proteid. The serious objection to their use, and especially uncooked, is the fact that they are grown in the sea-water around harbor entrances which are flooded with sewage, and hence they are likely to be contaminated with typhoid, or similar germs. The actual food value in shell-fish is quite small. They contain only about ten per cent of proteids, and are scarcely worth considering as a source of nutrition.