406 R. S. CUNNINGHAM 
is quite likely that still other variations than those described 
would become apparent if a larger series of dyes could be em- 
ployed, and they might prove of value in further subdividing 
the serosal cells into smaller groups. 
General serosal mesothelrum 
In animals acutely stained with trypan blue (1.e., having re- 
ceived six to eight doses), the cells covering the intestine, the 
body-wall, the liver, the mesentery, and the diaphragm had in 
common the distribution of dye-granules in a fine irregular, peri- 
nuclear rosette with a more or less evident concentra- 
tion at some area in the cytoplasm. There were a few scattered 
granules besides, usually just adjacent to the small clump. In 
animals’ having had only three to five doses, the perinuclear 
rosette was usually represented by an occasional granule and 
the small cytoplasmic clump at this earlier stage was present 
as a small irregular ring of granules. This ring was usually the 
first evidence of dye in the cell and often formed an almost per- 
fect ring or oval, usually about one-half or one-third the size 
of the nucleus. The most conspicuous individual differences 
between the individual surfaces included in this group, as shown 
in acute staining with trypan blue, were the greater number of 
diffused granules in the diaphragmatic cells, the more sharply 
formed ring in the mesentery, the greater tendency to perinu- 
clear rosettes in the liver, and the generally sharper localization 
and less amount of dye in the body-wall and intestine. These 
differences are given more because they indicate the relative 
lack of extremely sharp differentiation than because they seem 
of great importance within themselves. 
In animals in which staining was carried beyond eight to ten 
doses of trypan blue, the most important changes were a general 
increase in the amount of dye around the nucleus in all the cells 
of these surfaces except the diaphragm where there was a more 
definite increase in the granules diffusely scattered around the 
circumscribed area of earliest staining (fig. 2). 
