390 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
digestive gland, are numerous large spaces, crowded with 
blood corpuscles, amongst which are large spindle-shaped 
connective tissue cells, the ends of which are drawn out 
into long fibres. 
The epithelial cells lining the cavity of the stomach 
are very long and narrow, the length attained averaging 
about 0-‘OT mm ‘They have prominent elongated nuclei 
situated at about the middle of their length. These, like 
the epithelial cells throughout the whole length of the 
alimentary canal, are richly ciliated. 
If sections be cut transversely across the grooved 
epithelium it will be seen that the grooves and ridges are 
due to the varying height of the epithelial cells; those 
which lie at the bottom of a groove are only one-quarter 
of the height of those forming the ridge. The cell 
contents are the same in the two cases, and the cells at the 
bottom of the grooves bear just as well developed cilia, so 
that they apparently function as channels along which the 
secretion of the digestive gland passes. Some of the cells 
(but not those of the grooved epithelium) contain large 
and small green granules, which are sometimes as wide 
as the cell, and lie in a distinet vacuole. 
THE DIGESTIVE GLAND. 
This large gland (fig. 1, Dg.), which is the only one 
occurring in connection with the alimentary canal, has at 
various times been known as the liver, the Hepato- 
pancreas and the Gastric gland. The only function that 
entitles it to the name “liver” is that of apparently 
forming or certainly of storing fat and pigment. After 
much investigation, it now appears to be a “ pancreas ” 
with the additional function of storing pigment, and in 
some Lamellibranchs (Ostrea) large quantities of fat. It 
