Gr. H. Drew 
197 
Primary Carcinoma in the Liver of Rainbow Trout. 
Plate II. Fig. 1. 
Two out of the eight Rainbow Trout that were examined in 
connection with the disease of the swim bladder previously described, 
were found to have tumours in the liver. 
In one case the tumour was about the size of a large pigeon’s egg, 
and was situated in the posterior part of the left lobe of the liver. It 
was of a yellowish white coloui', and the surface appeared somewhat 
nodulated. On cutting it open two portions could be distinguished, a 
hard white fibrous looking area, and a softer part which showed small 
red points on the cut surface. The growth was not capsulated. The 
fish was a female of about If lbs. but was considerably wasted and in 
bad condition. 
In the other case the tumour was about the size of a pea, situated 
in much the same position as the former growth, unencapsuled, and 
homogeneous in structure. The fish was a male of about 1 lb. and 
appeared in good condition. 
The tumours were fixed in 5 °/o formalin, and serial sections were cut. 
Some were stained with haematoxylin and van Gieson’s stain, others 
with methyl violet, safranin, etc. 
On examining the sections it was seen that both the growths were 
very similar in structure : they only differed slightly in vascularity and 
in the amount of fibrous tissue present. Fig. 1 shows a section of the 
smaller growth. Toward the upper part of the figure the normal liver 
cells are seen, below this the cells and their nuclei are of a markedly 
larger size, and the nuclei show a great number of mitoses. The 
abnormal cells had slightly different staining reactions to the normal 
tissue, but they showed none of the staining peculiarities of amyloid 
degeneration. Scarcely any interstitial tissue was present in this tumour. 
Sections of the larger tumour showed an almost identical structure, with 
the exception that the harder portion contained more interstitial material, 
and the softer part was more vascular. 
No secondary metastases were found. 
Dr Bashford of the Imperial Cancer Research Fund, and Mr Strange- 
ways of the Pathological Department, Cambridge, have both been kind 
enough to examine sections of these growths and are agreed that the 
condition is one of primary adeno-carcinoma of the liver. 
Dr. Bashford states that it is the first case of the kind he has seen 
in fish. 
