Ovaries, Uterus, and Mammary Glands in Rabbit. 437 



Summary and Conclusions. 



(1) The development of the corpus luteum of pregnancy, or of pseudo- 

 pregnancy, in the rabbit is functionally correlated with the hypertrophy of 

 the mammary glands, as already shown by Ancel and Bouin, and by 

 O'Donoghue. 



(2) This hypertrophy is followed on about the 19th day after coition, in 

 pseudo-pregnant rabbits, by a definite secretion of milk, the quantity of 

 which may be temporarily augmented by the injection of pituitary extract, 

 just as in normal lactation. 



(3) The mammary hypertrophy can take place in rabbits from which 

 the uterus has been removed while still immature, thus showing that the 

 uterus is not an essential factor in the development of the mammary glands. 



(4) The development of the corpora lutea of pseudo-pregnancy is further 

 correlated with uterine hypertrophy and hyperemia followed by extravasation 

 of blood. 



(5) These uterine changes are clearly comparable to those which occur in 

 true pregnancy, and afford a confirmation of the view that the corpora lutea 

 are a necessary factor in causing and maintaining the raised nutrition of the 

 uterus during the first part of the period of gestation. 



(6) The changes which take place in the rabbit's uterus during pseudo- 

 pregnancy are homologous with those which occur in the uterus of the 

 marsupial cat during pseudo-pregnancy, and these latter are not pro-oestrous 

 in character (at any rate, in the earlier stages) as Hill and O'Donoghue suppose. 



(7) The domesticated rabbit is capable of breeding throughout the whole 

 year, but less frequently in winter than in spring or summer. If corpora 

 lutea of pseudo-pregnancy are produced, the recurrence of oestrus is postponed 

 until these are in an advanced stage of retrogression. 



(8) The shortening of the duration of the so-called corpus luteum spurium 

 of many mammals has probably been brought about in correlation with the 

 acquirement of the polyoestrous condition. 



The injections referred to in this paper were done by J. Hammond ; the 

 operations by F. H. A. Marshall. The work was carried out at the Field 

 Laboratories, Cambridge, in connection with the School of Agriculture. The 

 expenses have been defrayed by a grant made by the Board of Agriculture 

 and Fisheries out of money allotted to it, for purposes of research, by the 

 Development Commissioners. 



[Postscript, March 6, 1914. — In describing the results of hysterectomy we 

 omitted to mention that Foges found that the uterus was not a factor in the 

 pubertal growth of the mammary glands. 



