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



from May 29 to June 8, when bleeding appeared to have stopped. A very- 

 slight sanguineous discharge was, however, observed on J une 10, 11, 12, and 13. 

 The bitch was killed on July 26, 48 days after June 8, which probably 

 marked the end of the pro-cestrum, or 43 days after June 13, when all signs 

 of bleeding finally ceased. Fluid could be expressed from the nipples, the 

 mammary glands being well developed. 



The right ovary was seen to contain at least two corpora lutea. The left 

 ovary contained three corpora lutea, which occupied a large part of the organ. 

 Sections showed that the luteal cells were still large but much vacuolated, 

 and undergoing degeneration, but the nuclei were very distinct. 



The uterus presented a stage of retrogression considerably more advanced 

 than the previous stage. The epithelium lining the glands in some parts 

 (especially in the deeper parts of the mucosa) had undergone almost complete 

 destruction, that which was left was cubical and never columnar. The 

 cavities of some of the glands contained colloid and what were probably the 

 remains of desquamated epithelial cells. The changes which had taken place 

 had affected the blood supply, for many of the capillaries had broken down, 

 and there were corpuscles freely extravasated in the stroma (fig. 4). The 

 sections showed a resemblance to the late pseudo-pregnant stage described by 

 Hill and O'Donoghue for Dasyurus. 



Apart from the breaking-down of vessels and the presence of extravasated 

 blood in the stroma, the uterus showed no resemblance to the pro-oestrous 

 uterus, the condition of the glands being very different ; for, whereas the 

 glandular epithelium of the pseudo-pregnant uterus at this stage is degene- 

 rate, or else new and attenuated, that of the pro-oestrous uterus is columnar. 

 Moreover, in the sections of the pseudo-pregnant uterus there was no 

 evidence of blood passing into the uterine cavity, and there had been no 

 external bleeding from the vaginal opening of this bitch before killing. 



Sections through the mammary glands showed that these were in a state 

 of activity, the alveoli containing a quantity- of fluid, but we failed to 

 identify fat by staining with Sudan III. Since the bitch was muciparous 

 the sections were unsuitable for comparison with those of the virgin animals 

 described above, but it is significant to note that the glands must have 

 undergone growth in order to be in a condition of secretory activity. 



(8) This was a Fox Terrier, which was apparently a virgin. It had 

 probably been " on heat " at least once, but during the three months during 

 which it was under observation, " heat " had not occurred. The ovaries 

 contained numerous developing follicles but no luteal tissue. The uterus 

 was small, the mucosa relatively thin and with few glands or vessels. The 

 glands present were very small and lined by a cubical epithelium. The 



