CARCINOMA OF THE THYROID IN SAEMONOID FISHES. 
371 
Leven {S. kvenensis) during the spawning season of 1896. In 1898 about 2 per cent of the American 
brook trout over 3 years old would be affected and about i per cent of the rainbow trout over that age. 
I have no record of ever finding any diseased fish under 3 years old. 
With regard to the diseased specimens of rainbow trout which I brought to you recently, I visited 
the Masterton hatchery on June 16, when the manager was engaged in shifting his 3-year-old rainbow 
trout from their summer ponds into the spawning races, where they were sorted out, i. e., the male fish 
were separated from the females and the ripe female fish from the unripe; the ripe fish being stripped, 
and the unripe females and male fish being put into separate races. I assisted with the separating and 
stripping that day, when 1,200 fish were handled. From this number 29 fish affected with this gill 
tumor were taken out; these (with the exception of the specimens taken to your laboratory) were 
knocked on the head and buried. 
At the Otago Acclimatization Society’s Opoho and Clinton trout hatcheries the American brook 
trout are, I believe, the only fish affected with this disease, but at Christchurch hatchery I understand 
that it is common among both the American brook and rainbow trout. If it is of any interest to you I 
will get particulars from the Otago and Canterbury Acclimatization Societies with regard to this matter, 
and will also inquire whetlaer this disease has made its appearance at the Aukland Society’s hatchery 
at Okoroire, where only rainbow trout are kept. 
Gilriith quotes Ayson further as the authority for the statement that at Masterton 
he was present at the handling of 3,000 or 4,000 pond-spawning fish (1902) and that, from 
these, 100 fish affected similarly to those described were taken out and killed; also that 
the manager of the Aukland Society’s rainbow trout hatchery stated that 7 per cent of 
the mature pond fish at that hatchery were affected. 
Marsh in 1903 first reported the disease in the United States as an occasional 
occurrence known to fish culturists, affecting yearling as well as older trout, and noted 
the occurrence of marked anemia in affected fish. 
In the Third Annual Report of the Imperial Cancer Research Fund (English), 1908, 
in an article on the zoological distribution of cancer in fishes, occurs the following; 
Since the first authentic case of carcinoma in a fish, viz. , of the thyroid gland in a trout, was submitted 
to us in February, 1903, by Mr. Gilruth, over 2 ,cx 30 additional cases have been reported to us from the 
same and other hatcheries. * * * We have been unable to approach this extremely interesting and 
important subject from the fact that up to the present we have been unable to find any evidence of its 
occurrence in the hatcheries in this coimtry at the present time, the last epidemic of the disease appear- 
ing in 1888 in Scotland. 
At a meeting of the Lyon Medicale in 1908 Jaboulay reported having had in his 
laboratory for study six trout affected with malignant tumors of the thyroid gland. 
These were sent to him in November by M. Crettiez, inspector of waters and forests of 
Thonon. The disease had existed at the establishment at Thonon for three years and 
had been first noticed by M. Crettiez in salmon hatched from eggs received from Germany. 
He had recently observed the disease in sea salmon, ombres-chevaliers (Salvelinus 
alpinus), and in the offspring of one hybridization formed by crossing the common 
female trout with the male ombres-chevaliers, to which he had given the name Salmo 
thononensis. To Crettiez the disease appeared to be clearly hereditary and at the same 
time contagious and always fatal, although any elaboration of his grounds for these 
conclusions is not given by Jaboulay. Jaboulay considers the tumor an adeno-carcinoma 
of the thyroid, which he says invades the thyroid region and the neighboring tissues and 
in its last stages generalizes in the various organs. 
