SEA-FISHERIES LABORATORY. 93 
plasm is denser here and stains more deeply. In all cases 
a recognisable cell membrane appears to be quite absent. 
The distal cell protoplasm is very finely granular, and 
stains light red with methyl-blue-eosin; and it contains 
no inclusions except small dense black bodies. It is, 
however, possible that some of the latter may be situated 
on the outsides of the cells. 
This kind of hning persists throughout the entire 
length of both intestinal rami. 
Unicellular gland structures are present outside the 
intestinal wall, and in the mesenchymal tissue, but these 
are not abundant, nor do they present any features of 
much interest. At the anterior extremity of the body, 
however, there are two groups of cells which may be 
mentioned. ‘These lie near to the excretory vesicles, 
ventral and anterior to the latter, but they are not 
definitely circumscribed. They are represented in fig. 2, 
Pl. II (which shows part of a horizontal section of a 
worm fixed in Zenker’s fluid, and stained with methyl- 
blue-eosin) by the coarsely granular structures. They lie 
closely together, and though many of them are pear- 
shaped they do not usually seem to be provided with 
efferent conducting portions: the longest of these 
eranular cells is about 0°019 mm. But on tracing the 
group of cells in horizontal section from dorsal to ventral 
one comes to a plexus of thread-like anustomosing struc- 
tures, which he approximately in the same general plane 
and end by piercing the wall of the vestibule between the 
pharynx and anterior sucker. | These are doubtless 
continuations of the pointed ends of the cells, and the 
secretion of the latter probably passes along them to be 
discharged into the vestibule. The cells and plexus have 
the same general structure (both are shown in fig. 2, 
Pl. II), and they stain a deep red with methyl-blue- 
