along shore, the oyster growers have extended their operations into the deep open waters of Long Island Sound, the Chesapeake Bay, and to every coastwise state from Massachusetts to Texas and from Washington to lower California. The few small boats first employed, propelled by sails or oars, have given place to fleets of motor boats and steamers. In 1911 oyster planters spread 17,000,000 bushels of young oysters, shells and gravel over their 500,000 acres of oyster farms and harvested a crop of 15,000,000 bushels of oysters worth approximately $10,000,000. CLAMS.-Clams, like oysters, are found along the coast, and are most commonly used at the seashore. In composition they are very similar to the oyster. There are two principal varieties, the soft shell and little neck clams. Both are used for food. The soft shell is the favorite for "clam bakes," while the little necks are eaten raw, like oysters, or cooked in soup, broth or chowder. They have a pleasant flavor and their nutritive value is well established, but they are not as easily digested as oysters. SCALLOPS.-Scallops belong to the oyster family and are obtained along the New England coast. They are in season from September to March. The flesh of the scallop is very nutritious. Their use is contraindicated in diabetes, since they contain much glycogen. MUSSELS. -Mussels are bivalve mollusks. The common mussel is to be found in both salt and fresh water. Although used as food to a considerable extent, they do not, like oysters, form a dainty dish. Economically they are of more value for the pearls found in them than for their flesh. SNAILS. Snails deserve mention, as in some countries they are consumed as food in great quantities. They are hard, tough and indigestible, and must be made appetizing by the use of spicy condiments. They are unfit for the sick-room and have nothing in their favor for the hale and hearty. MILK AND MILK PRODUCTS Milk.-Milk is the secretion of the mammary gland and is confined to the mammalia. It is intended for the nourishment of the young animal whose mother secretes the fluid and contains all the ingredients needed for complete nourishment in just the right proportion which science and experience show should be contained in a well balanced ration. Milk contains proteins, which furnish the building material for the wear and tear of the body; fats and carbohydrates, which are the fuel to keep the body warm and furnish it with energy and power to do its work, and the necessary amount of water required by the body, all combined with the inorganic salts, without which life cannot continue. COMPOSITION OF MILK.-The composition of milk has been studied possibly more than that of any other food product. As a result, a large amount of reliable information is available. Milk is an opaque fluid, containing fat, 4 per cent; casein and various other proteins, 4 per cent; milk sugar, 4.5 per cent; mineral salts, 0.6 per cent; and water, 87 per cent. These are not filtered from the blood by the mammary gland, for milk sugar and casein do not exist in the blood. They are products of metabolism in the cells of the gland itself. These cells are rich in proteins and nucleoproteins, one of the latter yielding pentose and guanin. CASEIN. Casein arises by the union of the nucleic acid from the cell nucleus and serum albumin, thereby forming a nucleo-albumin, or, according to more recent classifications, a phosphoprotein. FAT.-Fat is a normal constituent of the protoplasm of cells. During the period of lactation the cells undergo a rapid fatty metamorphosis and the globules of milk are derived in this manner, being liberated by a destruction of cells. It is an unsettled question whether the fat of milk is set free, but it is probable that fats which have been assimilated from food are taken up by the cells. It is known that cattle secrete more fat than is contained in the food which they consume and it is evident, therefore, that it is produced by the metabolism of proteins and carbohydrates. MILK SUGAR. Neither is the origin of milk sugar clearly understood. We know that lactose is a disaccharid consisting of a molecule of dextrose and galactose, probably formed in the glands by a synthetic process. A large number of vegetables contain both these sugars. Physiology teaches us that the animal body is capable of transforming one kind of carbohydrate into another and we believe that some of the lactose may arise from the transformation of dextrose into galactose. SALTS AND SUSPENDED MATTER.-The salts are derived from the blood. The suspended matter is milk fat and a small proportion of casein in particles too fine to be arrested, except by stone filtration. COMPARISON OF MILK.-The following table, taken principally from König, gives the comparison of the milk of different animals. A study of the above comparative table shows woman's milk to be richer in sugar, but poorer in protein, than cows' milk, yet the fuel value is about the same. Dogs' milk appears to be the richest, whereas that of the mare is exceedingly poor. Not only is there a wide variation in the milk of different animals, but cows' milk, as we all know, is subject to great variations in the percentage composition of its component parts. As a rule, a young cow produces better milk than an old one and a well fed animal with free pasturage yields richer milk than one poorly fed, or one well fed and confined in a stall. THE FOOD VALUE OF MILK.-Unless otherwise stated our present studies refer to cows' milk. Federal government experts estimate that about sixteen per cent of the ordinary American diet consists of milk or milk products. These figures attest the value of milk and the very important place it has in the diet even for adults. The milk of the cow, therefore, is a very important foodstuff, being of a superior nutritive character. It is adaptable for combination with a large variety of other articles of food. MILK NOT A PERFECT FOOD.-The statement, without qualification, that milk is a perfect food is somewhat misleading, for while it may be a perfect aliment for the suckling, it does not necessarily meet all the demands of the adult. Besides milk contains more protein than is required by an adult. Again, it is rather too dilute a food for adult consumption, as it would require from four to five quarts daily to furnish sufficient. nourishment, which would be about equal to six ounces of bread or threefourths of a pound of beef. While it is quite true that it contains all the required elements for growth and development of the young mammal, yet it lacks certain properties which would make it suitable as a well balanced ration for the adult individual. It may be said, however, that it is too perfect a food for ordinary adult consumption, as every particle of it is assimilated, leaving no indigestible residue necessary for the normal action of the alimentary canal. ORGANIC AND INORGANIC CONSTITUENTS OF MILK.-The chief organic and inorganic constituents of milk and their percentages are graphically shown in the schemes of Van Slyke(11) and Babcock, Bulletin No. 41, Hygienic Laboratory: By this it will be seen that the average percentages of food elements in cows' milk is more nearly fat 4, proteins 3.5 and carbohydrates 5, than the 4, 4, 4 percentages usually calculated, in top milk formulas, or even 4, 3.5 and 4.5, as often followed. DIGESTION OF MILK.-Digestion of milk in the stomach is not accomplished as quickly as might be supposed. While milk is a fluid outside of the body, yet, when it enters the stomach, it is immediately coagulated by the hydrochloric acid and rennin of the gastric juice. These curds or coagula set into a hard clot formed by the precipitation of casein and a portion of the fat that has become entangled in the curd. Since the gastric juice is an acid fluid, it is surprising at first thought that curdling does not take place instead of clotting. That this does not happen can be explained by the fact that the alkaline salts of the milk neutralize the acid first secreted by the stomach, and gives the rennin time to act before the mixture has become acid in reaction. MILK CLOTS. These clots vary in size and consistence, depending somewhat on the quantity and dilution of the milk ingested. The casein is soon converted into some form of peptone and the fat is again set free. The albuminous covering of the fat globules is dissolved, coalesces and forms drops, in which shape it passes into the duodenum. A portion of the water and inorganic salts is absorbed by the stomach. After the clot of casein has once formed in the stomach it shrinks into a hard leathery mass, which offers great resistance to the digestive efforts of the organ. If the milk merely curdled, the act of digestion would be less difficult, for the particles of precipitated casein would be digested |