Received for Publication—June 17,1931

A i ^HE present paper reports an investigation of the self-chosen diets and JL the nutritive requirements of three multiparae during 60 weeks of intensive lactation, with special reference to the intake of calories, pro teins, fats, carbohydrates, calcium, and phosphorus in the food and the outgo of these substances in the milk secreted. These women produced an average of 1419 cc., 2366, and 3134 cc. of milk daily. In view of the cur rent empiric regimens recommended for lactating women, it is pertinent to consider the quantity of nutrients actually utilized in the secretion of milk. The principal organic constituents of milk, a secretion with a fairly con stant chemical composition for each species, are casein and lactalbumin, milk fat, and lactose. These constituents, peculiar to milk, are secreted by the mammary glands from precursors such as amino acids, phosphatids, and glucose respectively, in the blood. All the organic and inorganic con stituents of milk may be derived either from ingested food or from body tissue. Though inorganic elements, vitamins, and some drugs and other sub stances appear to be transferred directly to milk, food proteins, fats, and sugars do not ordinarily follow this course (1 to 11). Nevertheless, the woman who is producing an adequate amount of milk of good quality and doing so without any marked loss in body weight, must be transforming ingested food into milk. Meigs and Gary (12, p. 494) state