432 Mr. Hammond and Dr. Marshall. Correlation between 



means of identifying the individual rabbits previously referred to. The 

 respective ages of the rabbits, which prior to the occurrence of the recorded 

 coition were all virgins, have also been given above. 



(7) In a rabbit killed 3 days after sterile coition the uterine glands 

 were just commencing to undergo active growth. 



(8) In a rabbit of 5 days the glands were considerably developed and the 

 muscular walls had undergone some thickening. 



(9) In a rabbit of 9 days the process had been carried further (fig. 5). 



(10) In a rabbit of 12 days the uterine glands were more numerous and 

 smaller than those of No. 9. They were also more closely packed, and the 

 uterus showed congestion. The muscular walls were very thick. It is to be 

 noted again that the ovaries contained very old corpora lutea Csee above). 



(11) This rabbit had ovulated and corpora lutea were present, apparently 

 about 14 days old. The uterus showed a great development of glands which 

 were elongated and formed a spongy-looking mass at the base of the folds. 

 The muscular coat was thickened. 



(12) In a rabbit killed 16 days after sterile coition the uterine glands 

 were enlarged and spongy-looking. The capillaries in the stroma between 

 the glands were distended. The muscular layers were very thick. 



(13) In a rabbit of 24 days the uterine glands were smaller than those of 

 No. 12, but still very active. The folds of the mucosa contained a large 

 amount of extravasated blood, showing that the congestion had resulted in 

 a breaking down of the blood-vessels. The muscular coat was moderately 

 thick (fig. 6). 



The changes outlined above presented an essential similiarity to those 

 described by Hill and O'Donoghue for the pseudo-pregnant marsupial .cat. 

 There is a strikingly close likeness between the appearances which we 

 have just described (as shown in sections through the rabbit's uterus 

 during the successive stages) and the figures published in Hill and 

 O'Donoghue's paper on Dasyurits. In view of this great similarity there 

 can hardly be reason to doubt that the changes which take place in the 

 rabbit's uterus after sterile coition are physiologically homologous with the 

 changes which occur in the uterus of Dasyurus during the period of pseudo- 

 pregnancy. As will be shown subsequently the recognition of this fact, 

 which has not hitherto been pointed out, materially affects the views 

 entertained by the above-mentioned authors regarding the nature of the 

 homology between the oestrous cycle of the marsupial and that of the 

 Entherian mammal. 



Lastly, the hypertrophic changes which take place in the uterus during 

 pseudo-pregnancy are clearly comparable to those which occur in true 



