390 .TAS. p. HILL. 



Stage A. — P. nasuta. 

 Both uteri were somewhat enlarged, and presented a con- 

 gested appearance. In the right uterus an early blastocyst 



was found. 



The wall of the blastocyst was separated on one side from 

 the enclosing membrane (Selenka's '' granulosa merabran " 

 [2], Caldwell's shell membrane [3]) by a space, and had a 

 transverse diameter of '525 mm. ; while, including the invest- 

 ing membrane, the whole blastocyst had a diameter of "675 mm. 

 This blastocyst has not yet been examined in sections, but it 

 probably nearly corresponds to a ten hours' blastocyst of Di- 

 delphys, which, according to Selenka (2), has a transverse 

 diameter of about -5 mm. 



Microscopical examination of the right uterine wall shows 

 that as a whole it has increased considerably in thickness as 

 compared with the non-pregnant uterus. This increase is 

 mainly due to the enlargement of the mucosa, which now 

 averages 1*5 mm. in thickness. 



The uterine glands are closely packed together, causing the 

 interglandular connective tissue to appear greatly reduced. 

 They have increased both in length and in transverse diameter, 

 the latter now averaging -075 mm., and their epithelial lining 

 has undergone marked proliferation. It now consists of a 

 high cylindrical epithelium with numerous small deeply stain- 

 ing nuclei basally situated. The meshes of the connective- 

 tissue network are occupied by lymph coagulum, and numbers 

 of somewhat enlarged capillaries are also present, but as yet 

 in no great abundance. 



The most important change in this uterus, however, con- 

 cerns the lining uterine epithelium. Through the disappear- 

 ance of the cell outlines between the cells, it has become 

 transformed into a continuous protoplasmic layer or syncy- 

 tium all over the surface of the mucosa (fig. 2, syn.), and at 

 the same time it has increased somewhat in thickness, now 

 measuring '025 mm. 



Along with this fusion of the cell bodies, the nuclei have 



