LIGIA. 81 
formed by a single cell, the nucleus of which can be seen 
near the centre of the gland (n.c.d.). 
The hepatopancreas. ‘his is also known as the liver, 
and the digestive gland; the last name describes its true 
function. In Ligia it consists of three pairs of tubules, 
which extend from the pyloric region of the stomach to 
the posterior end of the abdomen, where they gradually 
taper off, and are generally doubled back for a short 
distance. The three pairs are situated in relation to the 
intestine, dorso-lateral, ventro-lateral and ventral (Pl. IL., 
fig. 16, v. hep.,vl. hep.). The muscles of the walls of the 
distal two-thirds of the tubules are so arranged, that a 
spiral appearance is produced. The spiral arrangement 
of the muscles no doubt aids their peristaltic con- 
tractions. The tubules of each side open into the 
pyloric region of the stomach by a single aperture, 
behind and below the ventro-lateral teeth. The two 
ventrally placed tubules of each side fuse and then open 
into the stomach. Anterior to the opening the 
dorso-lateral tubules curve ventralwards, and fuse with 
the anterior end of the ventro-lateral tubules. A small 
tube is given off from the front of the common hepatopan- 
creatic duct, which runs forward for a short distance and 
ends blindly. The epithelial cells of the hepatopancreas 
are of two kinds—large secreting cells containing large 
nuclei, and smaller cells which may be either young 
secreting cells, or cells of an excretory nature. 
The physiology of the digestive system of terrestrial 
Isopods has been studied by Murlin (1902). He finds 
that the secretion of the hepatopancreas, which may be 
liberated by the dissolution of the cell, fragmentation of 
the cell, or evacuation from the cell, contains ferments, 
which are able to act upon proteids, carbohydrates and 
fats. 
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