CARCINOMA OF THE THYROID IN SALMONOID FISHES. 371 



Leven (S. levenensis) 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 whether this disease has made its appearance at the Aukland Society's hatchery 

 at Okoroire , where only rainbow trout are kept. 



Gilruth 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, loo 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 2,000 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 country 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 (Sahelinus 

 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. 



