The mammary glands are indeed an integral unit of the female reproductive and sexual system. Were it not for the evolution and development of the function of these structures, it is conceivable that some form of life other than man would dominate this planet. In the female of our species the breasts are erotic centers, and, under certain circumstances, their stimulation may arouse different degreesof sexual excitement as well as induce contractions of the uterine musculature. Most important of all, however, they are the organs that assume the nourishment of the offspring after it emerges from its intrauterine habitat where it was maintained and nurtured through the maternal and placental vascular arrangement. Soon after nidation of the fertilized ovum, preparations are begun so that the breasts may take on their principal function some months hence when the mechanism of lactation is initiated almost simultaneously with the cessation of the mechanism