400 R. S. CUNNINGHAM 
reaction of these cells is most specific in character, even though 
the amount of dye stored is much less than in the case of the 
clasmatocyte, has suggested that this may be a method which 
will assist in solving some of the long-discussed questions regard- 
ing the relationships which the cells lining different areas of the 
peritoneal cavity bear to each other and to other cells. 
Goldmann, in his studies on vital staining, gives very brief 
consideration to the peritoneal lining cells. In one place (’12, 
p. 40) he states specifically that the ‘endothelial serosal lining 
cells’ do not store any vital dyes, and in another (’09, p. 45) 
he records the observation that the germinal epithelium of the 
ovary likewise does not stain in the living animal. 
Pappenheim (713) and Pappenheim and Fukushi (’14) agree 
with Goldmann that the peritoneal mesothelial cells do not take 
vital stains. They use this lack of the ability to store vital dyes 
as an argument against the participation of the lining cells in the 
formation of the free phagocytic cells of inflammatory exudates. 
Tschaschin (713) carried out experiments using collargol, isamine 
blue, and trypan blue, and states that he found that the serosal 
lining cells remained entirely unstained. 
That peritoneal mesothelium stains to some extent, however, 
when exposed to vital dyes has been noted by Schlecht, Evans, 
Kiyono, and Foot. Kiyono (’14) has given the most elaborate 
description of the vital staining of mesothelium, and his are the 
only illustrations of vitally stained serosal lining cells which I 
have been able to find. His figure (a), plate (1), shows two cells 
containing dye from animals which had been vitally stained by 
intravenous injections of carmine; these cells he designates as 
peritoneal lining cells, but he does not state from which surface 
they were obtained. Kiyono also studied the reaction of these 
cells to trypan blue in the omentum and found that the distribu- 
tion of the blue was precisely the same as that found for car- 
mine. He suggests that the reason the trypan blue granules 
have not always been found in the mesothelial cells is due to 
too long fixation, during which the blue diffuses out of the sur- 
face cells. He fixed his omental spread preparations for one 
hour and then studied them for the distribution of the dye. He 
