Ovaries, Uterus, and Mammary Glands in Rabbit. 427 



from the nipples. Two days later (July 16) the animal again underwent a 

 sterile coition. On the 17th day afterwards an attempt was made to express 

 milk from the nipples hut none could he obtained. On the 22nd day a little 

 serous fluid was obtained, and on the 28th day a considerable quantity of fluid. 

 The same day (August 13) the rabbit copulated a fourth time ; 24 days later 

 (September 6) no fluid could be expressed from the nipples, but two days 

 later (September 8) a few drops of serous fluid were obtained. The rabbit 

 copulated again (September 24) and is still alive. 



(18) A multiparous rabbit underwent a sterile copulation with a vasec- 

 tomised buck. On the 15th day after copulation no milk could be expressed 

 from the nipples. On the 20th day milk could be obtained in considerable 

 quantity. On the 22nd day the rabbit was again on heat and after undergoing 

 copulation was killed. The mammary glands were found to be full of milk. 

 Old corpora lutea and numerous degenerate follicles were found in sections 

 through the ovary. * 



(19) This experiment was with a multiparous rabbit and the result was 

 similar to that of the preceding experiment, there being no milk on the 15th 

 day, but some milk on the 20th and 22nd days, on the latter of which the 

 rabbit copulated again with a vasectomised buck (August 15). Twenty- 

 two days later (September 6) a few drops of milk were obtained, and two 

 days later quite a lot of milk was drawn off. The rabbit is still alive. 



(20) This experiment was upon a multiparous rabbit which was exceptional 

 in that no milk could be expressed from the nipples at any time during the 

 period between two successive copulations with a vasectomised buck. After 

 copulating a third time fluid could be expressed from the nipples on the 22nd 

 day and on the 24th day. 



(21) A multiparous rabbit was killed 17 days after a sterile copulation with 

 a vasectomised buck. The mammary glands were found to be well developed 

 but they contained no milk. 



It is thus seen that in pseudo-pregnant rabbits (that is, in rabbits in which 

 corpus luteum formation followed upon sterile coition) milk first made its 

 appearance about the 19th day after copulation. At about this period the 

 mammary hypertrophy appeared to have become complete and retrogressive 

 changes set in, anabolism giving place to katabolism, at any rate to a consider- 

 able extent. These changes took place in the absence of any observed activity 

 on the part of the myometrial gland, and it must be assumed that this gland 

 is not an essential factor in mammary development. Moreover the immediate 

 secretion of milk in considerable quantity followed by the characteristic 

 changes in the tissue of the mammary glands could be induced by the injection 

 of pituitary extract in the same kind of way as in normal lactation. 



