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



less so in the central and deeper portions of the stroma. There was no 

 longer any sign of haemorrhage, and no pigment was discernible. 



The mammary tissue showed very definite growth, being spread over a 

 considerable area, and not merely in the immediate neighbourhood of the 

 nipple. The lobes were constituted by numerous mammary acini separated 

 by connective tissue. There was every indication of rapid development 

 proceeding. 



(3) A multiparous brindled Terrier underwent pro-cestrous bleeding from 

 May 15 until May 23. It was killed on June 2, or ten days later. The 

 right ovary contained three or four corpora lutea, and the left ovary three 

 corpora lutea. Sections of one ovary showed that the corpora lutea were 

 fully developed and highly vascularised. 



The uterus was also highly vascular, the blood being contained within 

 capillaries situated in the middle portion of the stroma and between the 

 glands. The latter were very numerous, especially in the peripheral region 

 of the stroma, where there was little intervening connective tissue. They 

 were lined by a columnar epithelium (fig. 2). 



The mammary tissue, as was to be expected, was well developed, but the 

 animal being a multiparous one was unsuitable for purposes of comparison 

 with virgins in which the gland tissue showed different degrees of growth. 



(4) A Terrier bitch (a virgin) experienced pro-oestrous bleeding from 

 April 29 until May 7. Very slight bleeding continued until May 12. The 

 bitch was killed on June 2. The right ovary contained six corpora lutea and 

 the left ovary four. Each ovary was of relatively large size. Sections showed 

 that the ovaries consisted mainly of corpora lutea, which appeared to have 

 reached their full development. The luteal cells were much hypertrophied. 



The uterine mucous membrane contained vast numbers of glands, but 

 these were for the most part smaller and had a lesser diameter than in the 

 stages described above. The peripheral part of the mucosa was especially 

 packed with glands, but trabeculee of stroma tissue divided the glandular 

 elements in the more central part of the mucous membrane. The epithelium 

 surrounding the glands was still markedly columnar. Their lumina almost 

 invariably contained a colloidal substance which stained red with eosin. 

 There was a very considerable capillary development throughout the con- 

 nective tissue. 



The mammary tissue at this stage had developed appreciably. There was 

 a well-marked growth (in some places quite dense) for about f inch around 

 each nipple. Sections showed secretory aciniiin a further stage of develop- 

 ment, and cellular proliferation was proceeding. The intermammary tissue 

 was highly vascular, and there was a large quantity of fat present (fig. 6). 



