58 
Diseases of Fish 
there were considerable areas apparently consisting of fat cells 
resembling the tissue found in lipomata. Isolated fat cells were also 
scattered irregularly about in the sections. The nucleus of each cell 
was situated in the broader basal part. Owing to the length of time 
during which the tissue had been preserved in formalin, the protoplasm 
often showed marked vacuolation, and it was difficult to make out 
cytological details. The whole tissue somewhat resembled that found 
in the mammalian pancreas, with the exception that there was nothing 
corresponding to the cell islets of Langerhans. 
The liver was enlarged, and showed isolated nodules of a light yellow 
colour, slightly projecting from its surface. They were irregularly 
distributed over all the lobes, and in some cases measured almost half 
an inch in diameter. On cutting open the liver it was found that the 
nodules were also present in its deeper parts. Sections from different 
areas showed that the nodules were of the same nature as the large 
abdominal tumour, in fact histologically they were indistinguishable 
from it. In places the tissue of the nodules was not separated from 
that of the normal liver, but in other places there were indications of 
the presence of a thin capsule. 
In the normal fish the pancreatic tissue is embedded in the liver, it 
consists of a mass of cells surrounding the branches of the portal vein: 
occasionally one or two small nodules of pancreatic tissue are found 
outside the liver in the mesentery. In these cases, tissue of a well- 
marked pancreatic type often surrounds small spherical masses of cells 
which are probably the homologues of the islets of Langerhans in the 
mammalian pancreas. In the liver the pancreatic tissue is often 
divided from the hepatic by a thin fibrous capsule, but it is possible to 
find places where there is no such division. The pancreatic tissue is 
not described as ever extending to the surface of the liver, except 
immediately round the point of entry of the portal vein, nor have I been 
able to find evidence of its presence in such localities in normal livers. 
Thus it would seem that in these specimens there is an enormous 
hyperplasia of pancreatic tissue: the large oval tumour probably 
originated from a small mass of pancreatic tissue situated in the me¬ 
sentery, and the nodules in the liver were possibly partly derived from 
the pancreatic tissue normally buried in the liver substance, though it 
is difficult to explain the presence of the superficial nodules which are 
found in places not normally occupied by pancreatic cells. 
An explanation is to consider the condition an adeno-carcinoma of 
the pancreas, when it would be possible to account for the superficial 
