554 Dr. F. H. A. Marshall and Mr. E. T. Hainan. 



when present) is probably not so great in the pseudo-pregnant animal, but is 

 otherwise of the same general character. 



Ancel and Bouin were the first to show that the uterus undergoes active 

 changes in response to experimentally produced corpora lutea in the pseudo- 

 pregnant rabbit. They describe glandular hypertrophy and increased 

 vascularisation, followed by retrogression. The occurrence of these 

 changes was confirmed by Hammond and Marshall, who have pointed 

 out their essential similarity with the pseudo-pregnancy processes in the 

 uterus of the Marsupial Cat (Dasyurus), as recorded by Hill and O'Donoghue. 

 Hammond and Marshall show further (what is a corollary of the last 

 statement) that these changes in Dasyurus are not comparable to the 

 pro-oestrous phenomena of the Eutheria generally, as Hill and O'Donoghue 

 supposed them to be.* Neither Ancel and Bouin, nor Hill and O'Donoghue, 

 knew of Keller's work on the Bitch (confirmed and extended in the present 

 paper), and it is left to us to point out the parallelism between the 

 postcestrous processes in the three mammals in which they have been 

 described. 



Ancel and Bouin, and other investigators, have shown that in the Babbit 

 the postcestrous uterine development only takes place in the presence of 

 corpora lutea, which can be induced to form, without supervention of 

 pregnancy, by employing vasectomised males (i.e. under a condition of 

 experimentally induced pseudo-pregnancy). Moreover, the parallel series 

 of characteristic changes both in Dasyurus and in the Dog are always 

 associated with the development and subsequent retrogression of the corpora 

 lutea.f There can be little doubt, therefore, that the corpus luteum is an 

 essential factor in the hyperplasia of the uterine glands and other correlated 

 changes in these animals, just as it is in the Babbit. To prove this definitely 

 in the case of the Dog, it would be necessary to destroy the luteal tissue 

 while leaving the rest of the ovaries, but to perform this operation upon the 

 ovaries lying in situ in the body was, in our judgment, impracticable. 



The question arises as to whether there is any phase in the menstrual 

 cycle of Man which corresponds to the final or destruction stage of the 

 pseudo-pregnant period of the Dog. Bryce and Teacher and other authors 



* In the paper referred to we inadvertently omitted to note that in the scheme of 

 comparison drawn up by Hill and O'Donoghue to describe the cycle of changes in the 

 Marsupial and in the Eutherian the terminology is that of Heape, who was the first 

 to deal systematically with the phases of the cestrous cycle. Hill and O'Donoghue, 

 however, are alone responsible for identifying the uterine degenerative changes of the 

 pseudo-pregnant Dasyurus with the pro-oestrous changes of the Eutherian. 



t According to Moreaux, the presence of corpora lutea in the Eabbit's ovaries is 

 associated with an excretory phase on the part of the uterine glands. 



