422 R. S. CUNNINGHAM 
rabbit, do not offer any assistance in settling this point. On 
the other hand, the similarity between the reactions displayed by 
the cells of the germinal epithelium and the general serosal lining 
cells towards vital dyes suggest a closer relationship between 
these two groups of cells than has usually been assumed. 
SUMMARY 
1. The serosal lining cells have been found to store vital dyes 
in a very characteristic manner. The two most striking mani- 
festations of this reaction consisted in the localization of a con- 
centration of dye-granules in a circumscribed area of the cyto- 
plasm of each cell and in the formation of a perinuclear rosette. 
2. Mesothelial cells from different areas of the peritoneal sur- 
face presented certain peculiarities in their reactions to vital 
dyes which sufficed to classify them into groups, while they 
still conformed to the general characteristic type. 
3. The variations noted in the cells from different areas of the 
peritoneal surface consisted in differences in the amount of 
dye stored, the characteristics of the perinuclear rosette, and 
the orientation within the cell of the localized collection of dye- 
particles. The cells covering the intestine usually contained the 
least amount of dye, while those of the splenic mesothelium and 
the germinal epithelium of the ovary contained the largest 
amount. 
4. The germinal epithelium was found to store vital dyes in an 
especially characteristic manner. Each cell contained a round, 
oval, or cup-shaped mass of granules in the infranuclear zone 
of the cell; this mass, in well-stained animals, filled the entire 
portion of the cell between the nucleus and the basement mem- 
brane. On the other hand, the perinuclear rosette was found 
only rarely in the cells of the germinal epithelium. 
a, 
