INTERNAL SECRETION OF CORPUS LUTEUM 195 



stimulus. Similar results appear to have been obtained b}^ 

 Grueter (251), though details are not given by this author. 



The failure of Loeb and Hesselberg (403) to induce mammary 

 growth by injections of corpus luteum preparations was doubt- 

 less due to the mode of preparation (saline suspensions of 

 commercial dried tissue). Where autopsy is performed some 

 days after the cessation of the anterior pituitary injections a 

 copious secretion of milk is found. This shows definitely that 



Fig. 67. — Section of Gland shown in Fig. 66. 



secretion is precipitated by removal of the luteal influence and 

 not by the removal of a hormone present during pregnancy, as 

 postulated by Gaines and Davidson (235). 



Abnormal mammary secretion. Instances in which the 

 mammary glands function in quite abnormal situations and 

 at abnormal times are not uncommon. The new-born infant of 

 either sex quite often shows some abnormal mammary develop- 

 ment leading to the appearance of a certain amount of milk in 

 the ducts. The meaning of this is not entirely known, but it 

 possibly represents some activity on the part of the maternal 

 stimulus operating through the placenta upon the foetus. 

 Secretion by virgin animals is also not unknown (622). More 

 diificult to explain are the cases of mammary secretion in 

 the adult male (152). Many of these cases are doubtless of 



