Development of Mammary Glands in the Rabbit. 537 



(A) Cases in vjhich no Corpora lutea ioere Present in the Ovaries* 



(1) Multiparous rabbit. Small pieces of muscle, with the attached 

 mucosa, were removed from the uterine walls at short distances apart (to 

 represent foetal attachments) on the 9th day after coitus. Killed on the 

 25th day. Mammary glands consisted mostly of ducts, with a little alveolar 

 tissue. Openings in the uterus had closed up, and there was no decidual 

 formation. The glands were small and the blood-vessels were not enlarged. 



In the following cases (2-5) the rabbits had never been pregnant : — 



(2) Small pieces of uterus removed on the 9th day after coitus. Killed 

 on the 25th day. Ovaries very small. Uterus closed and infantile : no 

 decidual formation. Mammary gland consisted of ducts only. 



(3) Small pieces of the uterus removed on the 9th day after coitus. 

 Killed on the 28th day. Some very old corpora lutea seen in the ovaries, 

 winch could not have been the result of the last coitus. Uterus closed ; 

 glands small ; one fold of mucosa containing a few decidual cells. Mammary 

 glands atrophic, with a little milk in the ducts. 



(4) Uterine horns slit for whole length and pieces removed on the 7th day 

 after coitus. Killed on the 30th day. Uterus closed on one side but open 

 on the other. Mucosa showed small glands and congested capillaries, but 

 with very little proliferation of the connective tissues. Mammary glands 

 consisted of ducts only. 



(5) Uterine horns slit and pieces removed on the 7th day. Killed on the 

 31st day. Uterus closed in most places. Very few glands and blood- 

 vessels present, but one fold of the mucosa had swollen slightly. Mammary 

 gland consisted of ducts only. 



(B) Cases in which Corpora lutea were Formed in the Ovaries. 



(6) Eabbit not previously pregnant. Uterine horns slit and pieces 

 removed on the 8th day of pseudo-pregnancy. Killed on the 11th day. 

 Uterus open wide, glands of the mucosa large and active, capillaries dilated, 

 and decidual cell formation beginning in the connective tissue. Mammary 

 glands beginning to hypertrophy, but not thickened. 



(7) Multiparous rabbit. Uterine horn slit and pieces removed on the 

 7th day. Killed on 17th day. Uterus wide open, with large growths on the 

 mucosa, consisting of masses of decidual cells containing hyaline material. 

 Glands atrophic but blood-vessels dilated. Mammary glands well developed 

 but not thickened. 



* It has been noted in a former paper ('Eoy. Soc. Proc.,' B, vol. 87 (1914)) that 

 coitus is not necessarily followed by ovulation in the rabbit. 



