If the urgent admonition to mothers to nurse their infants is justified—and who will gainsay this advice-it becomes obviously important to secure adequate information regarding the physiology and pathology of lactation. Our knowledge of the phenomena of milk production in woman is far from extensive. Personal circumstances make it difficult, if not always impossible, to conduct experiments on the human being in order to learn the factors which modify the volume and quality of the secretion of the mammary gland, despite the evident need of first-hand evidence as to the possible variations in health and in disease. Consequently it has become necessary to depend on the outcome of studies on other species during lactation, and to apply these to human conditions so far as the analogies seem justified.
For evident reasons, the foremost observations on milk secretion have been made on cattle. That the volume of milk produced each day