far wrong in estimating cheese as one-third water, one-third fat and onethird nitrogenous matter. There is considerable mineral matter present in cheese, consisting principally of the salts of lime. In some cheeses we find a small amount of milk sugar.

The nitrogenous matter consists principally of proteins, but by no means entirely so. Stutzer estimates the following different forms in which nitrogen occurs in Camembert:

The exact proportions of these different nitrogenous bodies will vary considerably in different cheeses, but it is well to note the large amount of non-protein nitrogen present, which must be allowed for in an estimate of the nutritive value of cheese.

NUTRITIVE VALUE AND DIGESTIVE QUALITIES OF CHEESE.-Cheese is a most valuable storage food, rich in flesh-forming and energy-producing material. In fact, it is so rich in nitrogen and fat that a meal of bread and cheese supplies the needs of the system as well as an elaborate meal from soup to nuts. Cheese is a highly nutritious foodstuff. An infiltration of cheese with the fat which it contains must always render it an article of diet not easily digested, for the fat forms a water-proof coating which prevents the contact of the digestive juices with the casein. There are many people with delicate stomachs who cannot digest cheese at all. It is, on the other hand, a most valuable diet for people who lead an active outdoor life, or those whose digestive organs are healthy. With others, especially those who lead sedentary lives, a small piece of cheese at the end of a meal acts as a stimulant to the digestive organs, calling forth the muscular activity of the stomach, stimulating an increased flow of the gastric juice; to this extent it is an aid to digestion. To individuals who suffer from digestive disorders cheese is an enemy like any other indigestible article of food, and should be rigidly avoided.

Another reason, probably, for the disagreeable effects which cheese is apt to produce in the stomach is that, in the process of ripening, small quantities of fatty acids are produced, which are always very irritating. The stomach is the only digestive organ where difficulty is experienced. Once in the intestine, it is absorbed as easily and completely as meat.

For ease of digestion, cheese should be well chewed before being swallowed. It is a well-known fact that a hard morsel of food is more easily pulverized than a soft one, and for this reason a hard piece of cheese is more easily digested than a moist piece. The best way to serve Cheddar and American cheese is to cook it with macaroni or some carbohydrate food which will facilitate its proper mastication and prompt digestion. Williams, on the "Chemistry of Cookery," alludes to the chemistry of casein and the solubility of its compounds with alkalies, averring that the bicarbonate of potash seems to combine with the casein of the cheese, bringing the latter into a soluble state. The amount of bicarbonate of potash which will cover a dime is sufficient to dissolve a quarter of a pound of cheese, if the latter be first chopped into fragments. By adding milk and eggs to the grated or chopped cheese, with which the bicarbonate of potash has been added, a very savory and highly nutritious and easily digested pudding can be prepared.

There can be no doubt of the high nutritive value of cheese when one recalls that a pound of Cheddar cheese represents the total casein and most of the fat of a gallon of milk. We have already learned that cheese contains moisture one-third, nitrogenous matter one-third and fat onethird, in fairly equal proportions. The amount of moisture in lean beef is two-thirds, the balance being protein and fat, the former largely predominating. Beef, as will readily be seen, contains less than half as much nourishment as the same weight of cheese. Williams fathers the assertion that from a caloric point of view 20 pounds of cheese contains as much nutriment as a sheep's carcass of 60 pounds.

The fuel or caloric value of cheese as a foodstuff is high. A pound yields fully 2,000 calories of energy, which is more than three times the fuel value of a pound of moderately lean beef. Besides, a pound of cheese can be purchased at one-third the cost of three pounds of beef, which is its nutritive equivalent.

USE OF CHEESE IN THE INVALID DIET.-Cheese has its place even in the sick room. It renders good service in all cases requiring a strong concentrated nutriment, as in tuberculosis, neurasthenia, diabetes, convalescence, etc. By its savory, piquant flavor it lends itself charmingly as a means of modifying the milk diet in an acceptable and effective manner, except in Bright's disease and cardiac disturbances.

In dyspepsia, especially in the hyposthenic form, in enteritis and in enterocolitis, the easy assimilation of a certain quantity of the soft unsalted cheeses and their peptogenic and antiputrefactive elements is of decided value from a dietotherapeutic viewpoint.

SUBJECTION TO MOULDS RESULTING FLAVOR.-The types of cheese represented by the Cheshire, Canadian, American, English Cheddar, are subject to the action of certain yeast moulds and fungous growths, the nature and intensity of behavior of which vary with each particular brand. Their casein content is partially peptonized and partly transformed into a series of products more or less noxious, such as leucin, tyrosin, amino-acids and ammonia, whence they derive their odors and savory qualities that give each cheese its peculiar taste. Thus modified, cheese preserves the qualities of its peptogenic and assimilable substances, i.e., diastase, secreted by the yeast, seems to continue within the intestines, aiding the digestion of casein, and thereby losing completely its character of an antifermentative and slightly toxic food. Such cheeses are not advisable as a food in dyspepsia, enterocolitis, arthritis, heart and liver troubles and in Bright's disease.

MANUFACTURE OF CHEESES IN AMERICA. Of the cheeses manufactured in the United States, at least three-fourths are the ordinary American cheese, while among other varieties are the types of foreign brands, such as Neufchâtel, Stilton, etc. New York and Wisconsin together produce three-fourths of the entire output of this country. The 1909 census shows that not less than 320,532,000 pounds of cheese is made yearly in the United States. In 1910 Canada exported 186,000,000 pounds.

EGGS AND EGG PRODUCTS

Varieties of Edible Eggs.-Eggs of birds are used for food in all parts of the world, and so far as is known, the eggs of every species of bird may be safely consumed for food. The eggs of domesticated birds are used for food to a very great extent, especially those of the barnyard fowls: chicken, guinea fowl, ducks, turkeys and geese. Pheasants and guinea hens' eggs are considered a delicacy. Turkey eggs are as mild as hens' eggs. The guinea fowl's egg is smaller but more delicate than the hen's egg. Goose eggs are well flavored. Duck eggs are very rich and both are heavy and oily. The eggs of wild birds, such as the woodcock, plover and partridge, are especially sought after.

Besides the eggs of fowls and wild birds previously mentioned, the eggs of the turtle and terrapin are prized as a food as well as the eggs of fish.

Shad roe, especially, and the eggs of the sturgeon, preserved in salt and known as cariare, are considered a delicacy in some countries (see page 303). As may be assumed, the eggs of the heron and other sea fowl have a fishy taste.

FIG. 25.-APPEARANCE OF DIFFERENT GRADES OF EGGS BEFORE THE CANDLE The illustration shows (a) fresh egg, (b) stale egg, (c) fungous "spots" egg, (d) black (Yearbook U. S. Dept. Agric., 1911,

rotten egg.

Plate XLIX.)

These are enlarged one-third.

Eggs, like milk, form a complete food, that is, they contain the proper proportion of each of the fundamental food elements necessary to sustain and preserve life. Eggs and milk are the only examples of a complete food furnished by the animal kingdom.

COMPOSITION OF EGGS.-Hens' eggs are more largely consumed than those of other barnyard fowls and for this reason they will be referred to as the "type" under discussion. A hen's egg of average size weighs about two ounces, the weight being distributed as follows: the shell 11 parts, the white 58 parts, and the yolk 30 parts. The following table taken from Langworthy (22) shows the composition of the eggs of various fowls, both cooked and raw, and of white- and brown-shelled eggs, etc. AVERAGE COMPOSITION OF EGGS