94 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



sarcomata. These may have arisen by metastatic growth, 

 fragments of an original tumour having been distributed 

 through the lymph channels. But the general appear- 

 ance of the specimen suggests rather that the separate 

 sarcomatous nodules have arisen in situ independently of 

 each other, and one may perhaps suggest that this 

 affection, and perhaps most of those which I have 

 previously described as sarcomata in marine fishes, are to 

 be compared with the disease described by Gaylord and 

 Marsh* in Salmonoid fishes in American waters. Here 

 we have a condition of carcinoma of the thyroid becoming 

 endemic in fishes living free in populated waters. Some 

 fishes are immune to the infection. The latter is 

 apparently produced by some agent, or substance, 

 contained in the water inhabited by the fishes; and 

 notably in the tanks of hatcheries in which the fishes may 

 be bred or confined. 



It is, of course, difficult, or perhaps impossible, to 

 investigate such a possible causation in the case of such 

 fishes as Halibut or Rays, but it appears to be possible 

 that the origin of sarcomatous growths in marine fishes 

 living in the wild may be due to infection of some kind. 



Degeneration of Sarcomatous Tumours. 



There are no observations that I know with respect 

 to the rate of growth of malignant tumours in marine 

 fishes; and we do not know positively that such growths 

 as those which I have described ultimately cause the 

 death of the animals. Possibly sarcomata in marine 

 fishes may be of very slow growth, and the ordinarily- 

 caught marine edible fish is a short-lived animal — at 

 least, its duration of life prior to capture is usually a 



* "Carcinoma of the Thyroid in the Salmonoid Fishes." H. R. 

 Gaylord and M. C. Marsh; Bulletin of the Bureau of Fisheries, Vol. XXXII, 

 1912 ; pp. 365-524 ; Pis. LVI-CX. Washington, 1914. 



