170 Mr. W. Heape. [June 15, 



stroma has the appearance of embryonic mesoderm, the internuclear 

 protoplasm is drawn out into very delicate processes forming a con- 

 tinuous network ; there is no intercellular substance to be seen, and 

 a few long radial fibrils are present during the resting stage only. It 

 is a very primitive tissue. 



Period A. 



Stage I. The uterine epithelium is a single row of cubical cells; 

 its outer edge is sharply defined in section but the protoplasm of 

 the base of the cells is continuous with the protoplasmic processes 

 of the stroma. 



The glandular epithelial cells are columnar ; they rest on a base- 

 ment membrane but have no sheath. 



Bound nuclei are embedded in the protoplasmic network of the 

 stroma, which is evenly disposed for one- third of the depth of the 

 mucosa, while below that a few radially arranged fibrils occur. 



The blood vessels are small and fairly numerous. 



Period B. 



Stage II. An increase in the number of the nuclei of the stroma 

 by amitotic division and probably by fragmentation, causes swelling 

 and increase of density in the upper third of the mucosa hyperplasia. 

 Owing to pressure the nuclei become fusiform. An enlargement of 

 vessels takes place. No decidual cells are formed. 



Stage III. The mucosa is further swollen. The epithelium is 

 stretched and becomes thinner. Hyperplasia of the vessels directly 

 below the epithelium takes place and they are congested. 



The size of many of the nuclei of the stroma is reduced. 



Period C. 



Stage IV. Hypertrophy of the uterine epithelium of the stroma 

 and of the walls of the vessels appears all over the mucosa : followed 

 by degeneration in the superficial region, where the dilated, congested 

 capillaries break down, the blood contained therein being extra vasated 

 amongst the stroma. 



The degeneration is probably amyloid or hyaline, not fatty de- 

 generation. 



A considerable increase in the number of the leucocytes in the 

 superficial vessels takes place. 



There is no migration of leucocytes and no diapedesis of red blood 

 corpuscles, but where vessels are ruptured a few leucocytes are swept 

 out together with red blood corpuscles, into the surrounding tissue; 

 many leucocytes, however, remain attached to the remnants of the 

 walls of the broken-down vessels. 



