suspicion of the presence of the B. botulinus must be boiled before serving. Osborne and Mendel1 have found that when rats are fed yeast as the only source of protein and water-soluble B vitamines, the males are generally sterile. This is perhaps due to the effect of the insufficient diet on the endocrine glands. The part that the endocrine glands play in the disturbances of nutrition caused by privation of vitamines has not, as yet, been studied. PURINS The purin bases are xanthin, hypoxanthin, guanin, and adanin. These substances and uric acid are termed purin bodies. A nucleoprotein food yields nucleinic acid which furnishes purin bases and by oxidation forms uric acid. Uric acid may be produced by the breaking down and oxidation of the cells of the body (endogenous uric acid) and by the breaking down and oxidation of the nucleoproteins ingested as foods (exogenous uric acid). The amount of uric acid excreted in the urine represents largely the amount of purins ingested plus the amount of body nuclein breakdown. The amount of uric acid normally excreted by an adult on a mixed diet is from 0.30 to 0.50 Gm. daily, although he may excrete 0.30 Gm. on a purin-free diet from his own nucleolar breakdown. Some of the nucleoprotein or purin bases ingested are retained in the body or used for the building of cells. On a mixed diet about 2 per cent. of the nitrogen ingested is excreted as uric acid. At times, however, large amounts of uric acid are excreted, showing a sudden breakdown or destruction of body purins, namely, a nucleolar (cellular) loss as often occurs in leukemia. A purin-free diet means that a patient must not eat meat, fowl or fish in any form, except perhaps such shell fish as oysters and clams. Also he must not take tea or coffee, although coffee deprived of its caffeine is not objectionable. The glandular meats contain the most purin. These are the sweetbreads, liver, kidney, and roe of fish. Peas, beans and asparagus con1 Journ. of Biolog. Chem., 38, 1919, p. 223. tain purin in small amounts. The intestinal bacteria may destroy a certain amount of the purins of the food. MILK Milk deserves separate discussion, as it contains all the elements necessary to preserve life, especially for young animals. Cow's milk contains a little over 3 per cent. of protein, about 5 per cent. of carbohydrates, about 4 per cent. of fat, and something less than 1 per cent. of mineral matter, while about 87 per cent. of it is water. The protein is mostly (80 per cent.) in the form of casein, which is the protein of cheese and which contains a little phosphorus and sulphur. Another important protein is the lactalbumen, which is the principal protein of the whey. Though the casein is the more easily digested of these two proteins, the lactalbumen, which is lost in the making of cheese, has a distinct nutritive value. The butter fat of milk contains an important vitamine. The lactose, the milk sugar, besides being a valuable carbohydrate, tends to produce lactic acid in the intestine and to greatly increase the B. acidophilus, which germ checks putrefaction in the intestine. Milk also contains a large amount of calcium. Mother's milk contains all the elements necessary, including salts, for the growth and health of the child, but the constituency of human milk varies greatly at different times, especially in its nitrogen content. Human milk contains a little more fat than cow's milk and considerable less than goat's milk, while both cow's and goat's milk contain more casein than human milk. Human milk contains from 1 to 12 per cent. more milk sugar than that of the cow or goat. Cow's milk, then, as a food for infants contains more casein than is needed, less sugar than is needed, and, even when diluted, more salts than may be well tolerated by the infant, although if much diluted it contains an insufficient amount of iron. Hence when an infant receives a greatly modified cow's milk as a food, he may become anemic. Also it is a mistake to believe that the infant cannot soon digest small amounts of carbohydrates. Milk contains ferments which are more or less destroyed by heat, and although boiled milk is safe as far as being a germ carrier, it loses some of its vitamines, and, as Hess has shown, the antiscorbutic vitamine is destroyed by boiling, and scurvy may occur in a child fed only on boiled milk. Boiled milk is also constipating. To sterilize milk of all bacteria and most bacterial spores it must be subjected to a temperature of 212° F. for fifteen or twenty minutes. Some spores may even survive this temperature for this length of time. The health bulletin for April, 1920, issued by the Connecticut State Board of Health defines pasteurization as a process by which milk is rapidly heated to a temperature of not less than 142° F. and not more than 145° F., which temperature should be maintained between these figures for not less than thirty minutes, and the milk must then be immediately cooled to a temperature of not more than 50° F. Pasteurization will inhibit germ growth, but does not necessarily destroy bacteria. "Certified milk" should not contain more than 10,000 bacteria to the mil (c.c.) but like all other bacteriologic tests, variations in the report of bacterial content of a given milk occur when samples are sent to different laboratories, and a milk may be thoroughly good that has a much larger bacterial count. Also, it should be noted that milk may carry an infection even if the bacterial count is low. Therefore of very great importance are the conditions under which the milk is produced, handled, and marketed. Milk must not contain a preservative, not even sodium borate, and it must contain a certain amount of cream, and must not be diluted with water, to be marketable, according to the laws of most boards of health. The cow barns, the condition of the cows, and the cooling and bottling of the milk are all subject to sanitary laws. If a patient dislikes milk, its character may be changed by serving it hot, or diluted with plain water, barley water, an alkaline charged water, as vichy, or with a water charged with carbon dioxide gas. If salt is added to the milk, its character is changed. Junket may be made, or if desired the milk may be peptonized. Popular drinks to-day are skimmed milk and buttermilk. Buttermilk is the milk that is left after the fats have been removed in the process of making butter, while skimmed milk is the residue which is left after removing the cream. Skimmed milk has good protein value. Buttermilk tastes a little acid, and is generally made to-day for beverage purposes by adding lactic acid bacilli; the most used germs for this object are the Bulgarian bacilli. Various names are given to soured and fermented milks; the pleasantest of these milks are those that are sparkling and effervescent. A popular form in this country is termed koumys (also spelled kumiss), which is the name applied to fermented mare's milk in Asia Minor. It may be made at home by adding to a pint of milk two teaspoonfuls of sugar and about 16 of an ordinary yeast cake. This is put in a bottle and corked tightly, and should stand about ten hours in a place where the temperature is about 99° to 100° F. It should then be placed in a refrigerator, to be drunk as needed. Other names for fermented milk are yoghurt, which is the Bulgarian soured milk, kefir which is the name given to fermented cow's milk in the Caucasus Mountains, and matzoon is the name for the milk fermented in Syria. All of these fermented milks are very nutritious; but, like taking the Bulgarian bacilli too long for intestinal fermentation, they are likely to cause an increased acidity or at least a lessened alkalinity of body tissues, and should not be used too long without intermission. In other words, the lactic acid bacilli fad has been overdone. Also, there has been too much artificial alkalinization of infant foods. These alkalies can cause a loss of vitamines and reduce the antiscorbutic powers of milk, according to Alfred F. Hess, of New York. When it is advisable to add an artificial food to the milk for infants, the value of barley water and oatmeal gruel should be considered. Barley water is more or less constipating; oatmeal gruel or water, more or less laxative. Oatmeal also carries with it a little iron, and milk contains but a minute quantity of iron. Top milk as it is called, contains nearly twice as much fat as bottom milk, while skimmed milk contains only about one third of the fat that bottom milk contains. Whey of milk contains only a small amount of fat. CHEESE Cheese is a most valuable nutriment and is generally not difficult of digestion, the soft cheeses being more digestible than the hard cheeses; but if a hard cheese is completely masticated before swallowing, it also, will be easily digested. It should be remembered that not only milk, but cheese and butter made from milk may contain pathogenic bacteria. Cheese is nearly two-thirds of its bulk protein and fat, (from 25 to 35 per cent. protein) and thus is not only a builder of tissue and a substitute for meat, but also furnishes many calories of energy. Although Swiss cheese is made from goat's milk, it is being well made in this country from cow's milk. It is no longer necessary to depend upon imports for good cheeses; all varieties are now well made in America. Cheese should be more depended upon in this country as a valuable nutriment than has previously been the case. EGGS Eggs represent one of the most concentrated and satisfactory of foods. The nutritional value of an ordinary egg equals about the value of 150 grams of milk or 50 grams of meat, and furnishes about 80 calories. The food value of a raw egg is mostly only that of its yolk; the value of raw egg albumen is questionable. Raw egg albumen remains only a short time in the stomach, and passes rapidly down the intestines, hence feeding egg albumen during illness of any kind is a method of mythical value only, and such feeding should cease. It has lately been shown by Hawk and others1 that hard-boiled eggs, in spite of the antipathy against them, require but a few minutes longer for digestion than the time required for softboiled eggs. Scrambled eggs require a little longer time; fried eggs are digested as readily as soft-boiled eggs. Omelets take a little longer time for digestion. Poached eggs and shirred eggs are digested as readily as soft-boiled eggs. Rettger has shown that ovarian infection of hens may occur 1 Amer. Journ. of Physiol., July 1, 1919, p. 254. |