402 R. S. CUNNINGHAM 
lining cells as a distinct strain and state that the use of the azo- 
dyestuffs has furnished, in part at least, a means of differentiat- 
ing these cells. They do not give any very specific discussion of 
the characteristics which the surface-cells display other than 
that the granules are always minute and that the spleen manifests 
them in the most marked degree. That they have observed 
many of the characteristic differences which the cells lining the 
peritoneum manifest towards vital dyes is undoubted, and their 
opinion is clearly in favor of their specificity, but the analysis 
is insufficient for establishing any basis regarding the especial 
peculiarities of these cells. Undoubtedly an examination of 
these cells with a large number of dyes would yield further 
interesting facts. ‘ 
Ribbert (’04), Schlecht (’07), Goldmann (’09), Kiyono (14), 
and Evans (’16a, ’16b) have described the vital staining of 
the atretic follicle of the ovary. But none of these authors de- 
scribes any staining of the germinal epithelium, Goldmann alone 
referring specifically to these cells, stating that they do not store 
any vital dye at all. 
Foot (19, p. 366) reports the observation that the serosal 
cells from the omentum stain deeply with vital dyes, and uses 
this reaction to suggest their having a genetic relationship to 
free cells formed during inflammatory reactions. In a later 
communication (’21, p. 635) he describes the serosal lining cells 
of the omentum as containing a few fine granules, and concludes 
that most of the dye appears to pass through the cells. 
Most of the work that has been done on the cells lining the peri- 
toneal cavity has been directed to the solution of the problem of 
relationship between these cells and the free cells of inflammatory 
exudates. But the serosal lining cells are of interest in other 
connections, among these the most important are their relation- 
ship to fibroblasts and to the fundamental physiological activities 
in which the surface-cells are adapted to mediate. The phenom- 
ena of vital staining is of very great importance in differentiat- 
ing cell-groups from cell-groups and has already assisted very 
much in outlining the absolute separation of serosal cells from 
clasmatocytes. Can it also be used to assist in establishing 
PGR sere 5, 
