CELLS LINING THE PERITONEAL CAVITY All 
surrounded the nucleus parallel to its flattened surface, so that 
the condensation did not, as a rule, develop between the flattened 
surface of the nucleus and the surface of the cytoplasm, but rather 
it was adjacent to some point of the periphery of the nucleus. 
The numerous apparently different arrangements are all easily 
comprehensible if this fundamental type of the distribution of 
the dye is clearly understood. Despite the fact that in surface 
cells of the spleen the rosettes developed early and quickly, 
they contained only a small amount of dye before the condensa- 
tion of granules became the most obvious part of the staining. 
These collections of dye very rapidly increased in amount until 
in smear preparations the cells often seemed to contain only 
this single large mass of dye. The location of the mass of dye 
in relation to the nucleus was very interesting, and while every 
conceivable appearance was found both in smears and sections, 
careful study revealed that the dye-masses were, in the vast 
majority of cells, located lateral to the flat surface of the nucleus 
and near the termination of its shortest diameter in the per- 
iphery. The rapid increase in the mass produced the type of 
cap seen in figure 4, this cell having been selected because the 
perinuclear rosette was represented by only a few granules, 
while the entire lateral surface of the nucleus was covered by 
the dye. In animals having received about eight to ten injec- 
tions of trypan blue, this type of arrangement was very common, 
though more granules were usually present in the perinuclear 
rosette; the cells shown in figures 3 and 4 were both from an 
animal in this stage of staining. In sections from the spleen 
at this stage the nuclei of the mesothelial cells were bordered 
at either end, the ‘ends’ being obviously the optical appearance— 
rather than the anteroposterior poles—of the long axis of the 
nucleus, by groups of blue granules varying in amount from a 
small number to a large patch, practically filling the cytoplasm 
adjacent to the nucleus. The amount of the dye in such sections 
was obviously dependent upon where the section divided the 
cell in relation to the principal mass of dye. 
On further increasing the amount of dye administered, the 
edges of the principal dye-mass extended irregularly further and 
