Variations in the percentage composition of human milk are known to occur during the twenty-four hour day, but the desultory procedures followed in sampling the milk leave us without precise knowledge of the extent and nature of these fluctuations and their physiologic and clinical significance. Talbot1 suggested that the most characteristic picture of the composition of a milk can be ascertained from a sample taken at 9 or 10 in the morning. However, reports of wide fluctuations of milk fat at different nursings suggested that an entire day's production of milk should be collected in order to gain definite information on its characteristic percentage composition.2
Roberton3 aptly remarked that "Woman's milk varies in quality more than any other milk—a fact one might expect a priori from the endless variety and from the mode of living and circumstances of women." In view of the inconstancy in composition of