Chadbourne of this city and myself made some observations in order to ascertain how much food well-nourished infants receive daily. We selected infants that had an abundance of breast-milk, and weighed them before and after each nursing, so as to determine how much each infant took during twenty-four hours. The avoirdupois ounce contains 437.5 grains, and we ascertained by careful weight and measurement, employing the metric system for its greater accuracy, that one fluidounce of human milk, with a specific gravity of 1.031, weighed 451.9 grains. With these data it was easy to determine the quantity of milk in fluidounces from its weight. Our first observations related to 12 infants under the age of five weeks, 8 of which nursed twelve times, and the remaining 4 eight, nine, nine, and eleven times respectively, in the twenty-four hours. The quantity of milk received by them in twenty-four hours varied considerably in the different cases, but the average was 12.41 fluidounces. Therefore if a baby in the first five weeks nurse every two hours, it receives only a little more than one fluidounce at each nursing.

The next observations were made upon 15 infants between the ages of five weeks and ten months: 8 of the 15 were under the age of six months, and the remaining 7 were between the ages of six months and ten months. The weighing showed that the younger took nearly the same quantity per day, on the average, as the older infants in this group. The average quantity received by each was twenty-four and six-tenths fluidounces. Hence if the nursings were eight in the twenty-four hours, three ounces were taken at each nursing; if the nursings were twelve, the quantity each time was two ounces.

Biedert of Germany has also made similar observations in order to determine the amount of nutriment required by infants. The results of his weight-studies, as he designates them, were published in the Jahrbuch für Kinderheilkunde, xix. B., 3 H. His weighing showed that infants during their first month, if fed on cow's milk, required from 160 to 200 grammes of milk daily, and in the third month 300 grammes. These quantities in fluid measure are 5.44 to 6.83 ounces, the quantity required each day in the first month, and 10.22 ounces, the quantity required daily the second month. Therefore, both my weights and Biedert's show that infants under the age of two months assimilate a smaller quantity of milk than is usually supposed. For infants older than two months he estimates the quantity of milk required by infants by their weight. He believes that the greater the weight the greater is the amount of food which the infant needs. The method pursued by Chadbourne and myself is more simple, and it seems to indicate with sufficient exactness the amount of food required.

Some infants, like adults, need more food than others, so that there can be no exact schedule of the quantity which they require at each feeding; but while in the first and second months they do not need more than from one to one and a half fluidounces at each feeding, whether of breast-milk, or of cow's milk prepared so as to resemble as closely as possible human milk, infants as they grow older and their stomachs enlarge can take food in larger quantity, and therefore require less frequent feeding. Under the age of two months the stomach is so small that it cannot receive much more than one or one and a half fluidounces without undue distension. At the age of six months it can probably receive and digest without discomfort three ounces, and in the last half of the first year even four ounces. Infants nourished at the breast should be allowed to nurse every two hours in the daytime, whatever the age, after the second month, but less frequently at night, for frequent nursing promotes the secretion of milk, and the milk is of better quality than when it is long retained in the breast. If by the fifth or sixth month mothers or wet-nurses find, as is frequently the case, that they do not have sufficient milk, other food should be given in addition, perhaps after each second nursing or every fourth hour. The kind of food which it is best to employ to supplement the nursing will be mentioned under the head of curative measures. By knowledge on the part of the mother and nurse of the dietetic needs of the infant, and by consequent judicious alimentation, and by measures also to procure the utmost purity of the air, there can be no doubt that the summer diarrhoea may to a great extent be prevented.

Curative Treatment.—The indications for treatment are—1st, to provide the best possible food; 2d, to procure pure air; 3d, to aid the digestive function of the infant; 4th, to employ such medicinal agents as can be safely given to check the diarrhoea and cure the intestinal catarrh.

The infant with this disease is thirsty, and is therefore apt to take more nutriment in the liquid form than it requires for its sustenance. If nursing, it craves the breast, or if weaned, craves the bottle, at short intervals to relieve the thirst. No more nutriment should be allowed than is required for nutrition, for the reason stated above, and the thirst may best be relieved by a little cold water, gum-water, or barley-water, to which a few drops of brandy or whiskey are added.

Since one of the two important factors in producing the summer diarrhoea is the use of improper food, it is obviously very important for the successful treatment of this disease that the food should be of the right kind, properly prepared, and given in proper quantity. I need not repeat that for infants under the age of one year no food is so suitable as breast-milk, and one affected with the diarrhoea and remaining in the city should, if possible, at least if under the age of ten months, be provided with breast-milk. It can be more satisfactorily treated and the chances of its recovery are much greater if it be nourished with human milk than by any other kind of diet. If, however, the mother's milk fail or become unsuitable from ill-health or pregnancy, and on account of family circumstances a wet-nurse cannot be procured, the important and difficult duty devolves upon the physician of deciding how the infant should be fed. In order to solve this problem it will be well to recall to mind the part performed in the digestive function by the different secretions which digest food:

1st. The saliva is alkaline in health. It converts starch into glucose or grape-sugar. It has no effect upon fat or the protein group. It is the secretion of the parotid, submaxillary, and sublingual glands, which in infants under the age of three months are very small, almost rudimentary. The two parotid glands at the age of one month weigh only thirty-four grains. The power to convert starch into sugar possessed by saliva is due to a ferment which it contains called ptyalin.

2d. The gastric juice is a thin, nearly transparent, and colorless fluid, acid from the presence of a little hydrochloric acid. It produces no change in starch, grape-sugar, or the fats, except that it dissolves the covering of the fat-cells. Its function is to convert the proteids into peptone, which is effected by its active principle, termed pepsin.

3d. The bile is alkaline and neutralizes the acid product of gastric digestion. It has no effect on the proteids. It forms soaps with the fatty acids and has a slight emulsifying action on fat. The soaps are said to promote the emulsion of fat. Their emulsifying power is believed to be increased by admixture with the pancreatic secretion. Moreover, the absorption of oil is facilitated by the presence of bile upon the surface through which it passes.