igo INTERNAL SECRETIONS OF THE OVARY 



Ancel and Bouin (30), by removal of the corpora lutea after 

 sterile copulation, were able to show that this growth of the 

 mammary gland during pseudo-pregnancy is entirely dependent 

 upon these structures. 



Marshall and Hainan (449) have described the development 

 of the mammary glands of the dog during pseudo-pregnancy; 

 in this animal the constructive phase proceeds so far that the 

 breakdown process at the end of pseudo-pregnancy actually 

 leads to lactation. In Dasyurus the development of the 

 mammary glands during pseudo-pregnancy is indistinguishable 

 from that which occurs during true pregnancy; as in other 

 species the growth of the gland is correlated with that of the 

 corpus luteum. In the guinea-pig, according to Loeb and Hes- 

 selberg (402), the mammary tissue undergoes very little develop- 

 ment during the luteal phase of the ordinary dioestrous cycle in 

 the unmated animal, but there is appreciable growth when the 

 corpora lutea are caused to become abnormally persistent by 

 hysterectomy. During the dioestrous cycle, even when there 

 is a definite luteal phase, as in the guinea-pig, the develop- 

 ment of the gland is not normally carried far enough to result in 

 the actual secretion of milk. Woodman and Hammond (644), 

 however, report that virgin heifers after a series of dioestrous 

 cycles may occasionally secrete a small quantity of milk. 

 Dieckmann (159) has described the growth which takes place 

 in the mammary gland during the luteal phase of the human 

 menstrual cycle. None of the changes characteristic of the 

 luteal phase are found after ovariectomy or removal of the 

 corpora lutea. The control of this mammary development 

 during pseudo-pregnancy is known definitely to be endocrine in 

 nature. 



Our knowledge of the mammary gland during pseudo- 

 pregnancy makes it evident {a) that the presence of foetuses is 

 not essential for at least the initial phases of mammary develop- 

 ment, and (h) that since the only ovarian change in pseudo- 

 pregnancy is the development of corpora lutea, it is reasonable 

 to suppose that these bodies are the actual site of origin of the 

 stimulus required. The almost synchronized appearance of the 

 katabolic changes in the corpus luteum and in the mammary 

 tissue further supports this view. As a result of his study of the 



