SEA-FISHERIES LABORATORY. 203 
limes. Their cell substance is coarsely granular, with 
many round clear spaces; the nuclei are placed at their 
lower extremities. Only four to six cells are found in 
each group. The groups are delimited by the arms of the 
cross-shaped lumen, which extend nearly to the walls of 
the tubule, and here at the thinnest portion of the wall 
the cells composing it are small and irregular, and have © 
relatively large nuclei. If the section has been stained 
with Heidenhain’s haematoxylin a very distinct basement 
membrane, staining dense black, can be seen investing 
each alveolus. The whole mass of the gland is bound 
together by fibrous connective tissue, in the interspaces of 
which are crowded corpuscles of various kinds. 
The lining epitheliuin at the animal’s mouth consists of 
elongated columnar cells bearing cilia, and supported on a 
rather distinct basement membrane. Passing inwards this 
epithelium is thrown into a close series of longitudinal 
folds, and the height of the cells diminishes. The cells 
have distinct striated free borders, the nuclei are situated 
about their middle, the lower ends are rather loose and 
seem separated from each other; rounded faintly granular 
eosinophilous cells are found here and there wedged in 
between the columnar cells. 
As the cesophagus widens out to form the stomach 
these cells gradually elongate to form the epithelium 
lining the cavity of the latter. This gastric epithelium 
(fig. 18, Pl. III.) is of variable thickness, but the cells are 
always longer than in the csophagus. A gelatinous 
looking substance—the “‘fleche tricuspide” (Ff. trv., 
fig. 18)—lines a large portion of the stomach-wall, and 
underneath this the epithelium becomes much thicker, 
consisting of long spindle-shaped cells, the long oval nuclei 
of which occupy any position within a rather wide zone 
about their middle. The lower ends of these cells are 
