Caloric value per kilogram, 700 calories. Physical characteristics of cow's milk. Its color is white, varying from a clear to a yellowish white. It is very opaque, the opacity being due to its large content of calcium in combination with its casein. Its specific gravity varies from 1.028 to 1.033 with an average of 1.031. Its taste is pleasant and charateristic. The addition of acetic acid causes a flocculent precipitate, and on the addition of rennet it coagulates into a firm mass. Reaction. When freshly drawn this is amphoteric or slightly alkaline; on standing it soon becomes acid. Proteids. The proteids of cow's milk consist mostly of casein in combination with calcium. As in woman's milk, lactalbumen is also present but in small quanity. According to Koenig, casein is present in the proportion of 7 to 1 as compared to lactalbumen. Fat. The fat in cow's milk is the element that is most subject to variation, as the content of the other food elements is remarkably constant. A milk poor in butter fat contains about 3 per cent, while a rich milk, such as milk from Jersey cows, contains 5 to 5.25 per cent of fat. It is highly important to know the percentage of fat present in milk actually being used for the feeding of infants for reasons discussed later on. The sugar of cow's milk is practically identical with that of woman's milk, and is present in the proportion of about 4.50 per cent. Salts.--Inorganic salts are present in the proportion of 0.75 per cent, of which calcium and phosphoric acid are the most abundant constituents. Bacteria.-Cow's milk always contains a large number of bacteria, their number increasing with the age of the milk and the conditions. under which it is kept. Cream.-Cream is merely cow's milk rich in fat to excess. It is obtained either by skimming the milk (gravity cream) or is separated from it centrifugally by a machine known as a separator. It differs from milk but slightly in its other solids. Very rich cream (40 per cent) contains relatively less sugar and proteid (sugar 3 per cent, proteid 2.20 per cent). The usual strengths of separated creams marketed contain respectively 8 per cent, 12 per cent, 16 per cent, 20 per cent, and 40 per cent of fat. PART III.-INFANT FEEDING. NUTRITIVE REQUIREMENTS OF INFANTS. It is obvious that any inquiry into the methods of infant feeding demands an intelligent comprehension of their nutritive requirements. Yet this phase of the question has been the object of scientific study only of recent years. Why this has been so, it is difficult to understand, seeing that we have long been possessed of very precise data as to the calorific value of the various articles composing the adult's dietary and the amount of heat units required to maintain their nutrition under various circumstances. And yet, until the investigations of Heubner and his co-workers, our knowledge of the nutritive needs of infants has been mainly empirical and based merely on clinical observations, observations which I may add have been the source of serious error. The world is indebted to O. Heubner of Berlin, who was the first of a series of investigators, now rapidly increasing, for the discovery of facts which go a long way toward solving the difficult problem of infant feeding. Heubner," appreciating that the principles underlying the feeding of infants, could only be worked out, as in the case of adults, from the logical basis of the number of calories per kilogram of body weight required by them for the purposes of growth and nutrition, undertook a series of exhaustive experiments with this end in view. Like most fundamental investigations, his line of procedure was quite simple, being merely to determine the daily amounts nursing children took at the breast, each day for successive months, to tabulate the daily and weekly gains observed and finally, to determine by chemical analysis the composition, and from that the calorific energy of the milk that produced it. His results show that on the average, nursing infants, in order to thrive, require the following food value, or energy quotient as he calls it, per kilogram of body weight: First week in life, 60 calories per kilogram of body weight; first three months, 100 calories per kilogram of body weight; second three months, 100 to 90 calories per kilogram of body weight; third and fourth three months, 80 calories per kilogram of body weight. His results were confirmed by Feer, Nordheim, Beutner, Czerny, Keller, and others. He also found that an energy quotient of 70 was a O. Heubner, Die Energiebilanz des Säuglings. Zeitschrift f. diätet. u. physik. Therapie, 1901, Vol. V, p. 13. This term, as used in this paper, refers to large calories, or the amount of heat requisite to raise 1 kilogram of water 1° C. in temperature. the minimum on which a child of less than 1 year of age could maintain its weight. Any diminution of the quotient below this level was followed by a loss. Moreover, the researches of Czerny and Keller have shown that the energy quotient of 100 calories per kilo of body weight marks an upper limit which can only be temporarily surpassed without inducing disastrous nutritive and gastrointestinal disturbances. These disturbances will be later discussed under the head of "overfeeding." A necessary part of these researches was the determination of the caloric value of mother's milk. As human milk varies in composition not only in different individuals but at different stages of its secretion from the breast, only average values could be found. According to the richness of the milk, it varied from 614.2 to 723.9 when lactation was fairly established with an average caloric value of 650 to the kilogram. The determination of the caloric' value of any food substance is very easy once we know its percentage composition as one gram of fat produces 9.3 calories and one gram of proteid, and one gram of carbohydrate have each a caloric value of 4.1. Thanks to these investigations we are now in a position to determine most exactly, if desired, the amount of food required by each individual child in order to nourish it and give it growth and have furthermore, data by which we determine whether it is getting too much, in time to avert the disastrous consequences. METHODS OF FEEDING INFANTS. There are three methods by which infants may be fed (a) maternal nursing, (b) mixed feeding, part maternal and part artificial, and (c) artificial feeding exclusively. MATERNAL NURSING. Importance of maternal nursing. The importance of maternal nursing can not be overestimated. Were mothers able universally to nurse their children, one-third to one-half of infant deaths would be expunged from our mortality returns. The number of women capable of nursing their children is probably greater than is supposed. Von Bunge's' statistics, gathered from all parts of Europe, tend to show that probably 75 per cent of all women could nurse their children. I have already adverted to the German city of Barmen where 63 per cent of all infants are fed at the breast. Professor Budin's statistics of the Clinique Tarnier in a Czerny and Keller, Des Kindes Ernährung, Ernährungsstörungen und Ernährungstherapie. Von Bunge, Die zunehmende Unfähigkeit der Frauen ihrer Kinder zu stillen. Budin "The Nursling." Paris show that 448 out of 557 women who attended were able to nurse their children. The importance of maternal nursing is well recognized in France both by the Government and by commercial interests. The effect of this encouragement upon public sentiment has been marked and in some of the industrial districts of France where formerly the artificial feeding of infants was the rule, it has now become the exception. In most of the factories of that country employing women, notices are conspicuously posted setting forth the advantages of maternal nursing. In many of these establishments rooms are set apart, wherein mothers nurse their children, and they can always obtain leave of absence at appropriate intervals for the purpose of suckling their infants. In Italy a law has been passed compelling each industrial establishment employing 50 or more women to furnish rooms for this purpose. Causes preventive of maternal nursing.-Three causes are mainly operative in depriving infants of their right to the breast. First, physical inability on the mother's part to nurse her child; second, inability on her part by reason of her engagement in some industrial pursuit; and third, disinclination, chiefly by reason of the trouble maternal nursing involves and the divorce it necessarily entails from social pleasures and pursuits. Von Bunge has shown that apart from local and systemic disease, alcoholism seems to be the chief cause, in any country as a whole, which renders mothers as a class unable to nurse their children. The daughters of the third generation of alcoholics are usually unable to suckle their young. The second condition referred to, i. e., the engagement of the mother in some industrial pursuit, depends in a great measure upon the willingness of husbands to accept the earnings of their wives at the expense of their children, or upon their failure to provide for them. This forces the mother to work for her bread while her child is turned over to the tender mercies of some stranger and the milk bottle. Much can be done by general popular enlightenment to eliminate the third cause, namely, the disinclination of mothers to nurse their children. It is hardly to be supposed that any woman will refuse to nurse her baby from purely selfish considerations, once she is fully informed of the enormous advantages it confers upon her child. It is obviously the duty of the medical profession to further this by every means at their command. In view of the foregoing, every mother should nurse her child unless there are cogent reasons to the contrary. The following causes may be mentioned as contraindicating maternal nursing: (1) Tuberculosis, latent or active, affecting the mother. By nursing the child she can but accelerate the progress of the disease besides exposing the child to the danger of contracting it. (2) When the mother is affected by grave, chronic, or systemic disease. (3) When the mother is choreic or epileptic. (4) If she has suffered from any severe complication of the parturient state such as hemorrhage, eclampsia, nephritis, puerperal septicæmia, and the like. (5) Local disease of the mammary gland. (6) When as the result of two previous experiences under favorable conditions she has shown her inability to nurse her child (Holt). (7) When no milk is secreted. Care of the breasts during lactation.-In order to prevent local affections both of the mammary gland and the infant's mouth, it is highly important that particular attention should be paid to cleanliness. The nipples and breasts should, therefore, be carefully washed prior and subsequent to nursing, either with plain water or boric-acid solution. Nursing during childbed.—A newborn child should be nursed once in six hours the day following delivery and once in four hours the succeeding day. This is necessary (1) to accustom the child to take and the mother to give the breast, (2) to empty the breasts of colostrum, (3) to promote the involution of the uterus. The colostrum furnishes the child with all the calories necessary to its needs until the lacteal flow is established, nor does it need any other food. The usual practice of feeding a newborn child with decoctions, of various sorts with the object of alleviating the colic supposedly indicated by its cries is absolutely to be prohibited. The crying promotes the full expansion of the lungs and the establishment of normal circulation. Plain boiled water, however, may be freely given, as the body fluids of the newborn are in a concentrated state. Regular habits of nursing.-Much more is dependent upon the early establishment of regular nursing habits than is supposed. They are as easy to initiate as the irregular, and by so doing much of the strain of lactation upon the mother can be eliminated. This is highly desirable in view of the beneficial effect a calm and equable state of mind and adequate time for rest and sleep have upon the lacteal secretion. Moreover, the milk is more likely to be of a uniform character throughout lactation when the breasts are drawn upon at intervals definitely spaced. A young infant can usually be expected to take a long nap of some four or five hours during some period of the twenty-four, and it is just as easy to have this secured at night. In order to promote the uniformity of lacteal secre |