The Phosphatide and Total Phosphorus Con- Tent of Woman’s and Cow’s Milk

Recent, studies have made it evident that phosphorus plays a more important Ale in the metabolism of infants, more especially in the metabolism of bone, than had been realized. It is therefore of increasing interest to inquire closely as to the distribution of the phosphorus in t,he dietary of the growing child. This naturally implies a study of milk, which forms the sole constituent of the dietary throughout the first 6 mont,hs of life and its basis during the following year. Investigations of the total phosphorus of milk have been numerous, whereas studies of its phosphatide fraction have been very limited, and, for the most part,, were carried out many years ago. The significance of phosphatide in t.he diet is still a mooted question; it. should be borne in mind, however, that some investigators regard it as an essential and irreplaceable diet,etic factor. What.ever may be the view-point in this regard, it must. be remembered t’hat it is a constituent of almost all the cells of the body, and that in the human blood organic phosphorus constibutes over 80 per cent of the total phosphorus, and inorganic phosphorus only 3 to 4 mg. per cent. Studies of the phosphatide of milk have given most varied results, which is not, surprising considering the diversity of the methods employed. It would serve no purpose to enumerate or review these investigations in detail. The most reliable is probably that of Koch and Woods published in 1905 (1). The superiorit,v of this work rests on the fact that the milk was not dried and that care was exercised not to include any water-soluble extractives, inorganic phosphates, phosphorus in simple organic combination, and inorganic salts in the final precipit.ation. Since these analyses