318 Records of the Indian Museum. [VoL. XI, 
Unfortunately only spirit specimens were available and hence 
I have been unable to make observations on fresh material. Sec- 
tions were made from one of the larger tumours. These tumours 
are undoubtedly due to a disease of the thyroid variously known 
as gill-disease, thyroid tumour, endemic goitre and carcinoma of 
the thyroid. The disease was first noted in 1883 by R. Bonnet 
(t)'—in Tyrutta lacustris obtained from a hatchery in Torbole on the 
Gardasee. ‘The disease accounted for the death of 3000 fish. 
The first investigator to define the tumour as Carcinoma was 
Scott (9) who found it in Salmo frontinalis from ponds at Opoho 
belonging to the Dunedin Acclimatisation Society, New Zealand. 
In 1902, Marianne Plehn (8) recognized that the tumours 
were due to a disease of the thyroid gland. In 1903, L. Pick (70) 
described the disease fully. Gilruth (3) in the reports of the 
New Zealand Department of Agriculture (Veterinary Division, 
Igor and 1902) described a similar disease in Salmo salar as 
‘‘ Epithelioma affecting the branchial arches of Salmon and Trout.”’ 
Later, this author recorded the disease from Salmo trideus. 
L. F. Ayson, Chief Inspector of Fisheries, New Zealand, stated 
in a letter to Gilruth that he had noticed the disease in Salvelinus 
frontinalis in 1890. In 1908, Jaboulay (5) reported the disease in 
six trout from Thonon. Up to the present, five species of fish from 
Europe and 21 species from America have been recorded suffering 
from the disease. In America the disease appears to have been 
known for a long time although not described until 1909, when 
Dr. Gaylord read a paper on ‘‘an epidemic of cancer of the 
thyroid in brook trout’ before the American Association for 
Cancer Research. The initial investigations into diseased thyroids 
in the Salmonidae by the American Association for Cancer Re- 
search were due to the papers on the subject which had previously 
appeared by Plehn and Pick. 
The Association continued to make extensive observations on 
the disease, and an excellent and exhaustive report on the subject 
was published in the Bulletin of the Bureau of Fisheries vol. 
XXXII, 1912 (“‘ Carcinoma of the Thyroidin the Salmonoid fishes,” 
by Harvey R. Gaylord, etc., Doc. No. 790. Issued April 22, rgr4). 
To these authors I am indebted for most of the details set forth in 
the present paper. In Salmonoid fishes the thyroid is a more or 
less diffuse, unencapsuled organ, distributed along the course of 
the ventral aorta. The gland, however, appears to be much more 
diffuse in domesticated trout than in wild trout. Gudernatch 
states that in wild species the gland may extend into the gill- 
arches and even into the muscle bundles of the isthmus. This 
circumstance serves to explain the fact that tumours may be found 
in places as far removed as the jugular pit and the rectum. The 
disease is universal where trout are artificially cultivated, and in 
certain hatcheries it may become endemic. Artificial cultivation 
is obviously a predisposing factor since the disease is rare in nature. 
' ‘These numbers refer to the literature cited on p. 320. 
