No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 483 
cell. The cell has thus no external openings and no ducts or 
fibers which penetrate into the enveloping tissues. 
19. Subcutical Gland Cells of Piscicola rap ax (Verr.). 
(Plate 25 ; Plate 26, Figs. 198-203.) 
(These cells lie for the most part in the body cavity, between 
the body muscular wall and the intestine. Two modifications 
of them may be distinguished : (1) those at the ends of the 
body, near the suckers and in the wall of the latter, which are 
comparatively small, and the relatively short cell ducts of which 
open at all points of the surface of the body at the ends of the 
body and on the inner surface of the suckers; these seem to 
resemble the second modification in all respects except size ; (2) 
the larger type of these gland cells, which I have studied exclu¬ 
sively, are massed together in that portion of the body cavity 
which extends from the region a little anterior to the brain, 
nearly to the posterior end of the body, the greater number of 
them being in contact with the inner surface of the body 
wall.) 
In order to find all the functional stages of these cells one 
must study preparations of worms of various dimensions, since 
all the stages cannot be found in a single individual ; I made 
consecutive series of sections of seven different individuals, the 
smallest being about 6 mm. in length, and the largest being fully 
matured. The remarkable cycles of the nuclear and cell stages, 
to be described below, were equally well discernible with all 
three of the fixatives employed, namely, Flemming’s fluid and 
alcoholic and aqueous solutions of corrosive sublimate ; various 
double stains were used. 
These cells, when they reach their fullest dimensions, are so 
enormous that they may be readily seen with the naked eye. 
Their single ducts all open on the surface of the body, between 
the epithelial cells, a little anterior to the region of the sexual 
pore ; their openings are at this point equally numerous on 
the dorsal, lateral, and ventral sides of the worm. The most 
posterior gland cells of the body send their ducts a distance of 
four-fifths the total length of the body before they open on the 
