CARCINOMA OF THE THYROID IN SALMONOID FISHES. 415 
Besides the American brook trout and the rainbow trout introduced into Europe, 
the following European species, at least, have been observed as the subject of thyroid 
carcinoma in Europe : 
Atlantic salmon Salmo salar Linnaeus. 
Forelle; Bacliforelle ; brown trout, yellow trout, brook trout, 
river trout, etc Salmo fario Linnsus. 
Loch Leven trout Salmo levensis Walker. 
Seeforelle or lake trout Salmo lacustris Linnaeus. 
Ombre chevalier, European charr or saibling Salvelinus salvelinus (Linnaeus). [Salve- 
liiius alpinus (Linnaeus) of most authors.] 
GEOLOGICAL FORMATION AT FISH HATCHERIES. 
That the distribution of goiter possesses a definite relation to the geological for- 
mation has been repeatedly advanced and denied. McClellan in 1837 pointed out the 
predisposing quality of the mountainous limestone and the nagelfluhe. The principal 
exponent of this theory in Europe has been H. Bircher (1883). According to this author 
the greatest concentration of goiter is found in the Molasse highland. The Tertiary 
formation also predisposes to goiter, whereas the Jurassic formation and the primary 
formation of the Alps are free from the disease. Kocher (1889), who with the assistance 
of 25 of his scholars examined 76,606 school children between tlie ages of 7 and 15 
years, was not able to justify these conclusions of Bircher, as he found that the Jurassic 
formation was in no way free from goiter, neither was the fresh-water Molasse. Recently 
Hesse (1911) in a study of the distribution of goiter in the Kingdom of Saxony, was 
able only in part to confirm the theory of Bircher, as he found next to the highest per- 
centage of the disease in the Eibenstock granite and the highest in the ei'uptive Mus- 
covite gneiss, both of which are formations that according to Bircher should be free 
from the disease. Schittenhelm & Weichardt, in the study of goiter in Bavaria (1912), 
found that one of the most extensive distributions of goiter in that country was in 
the Bavarian forest, which lies upon the primary granite formation. These authors 
conclude that the geological formation is not a primary determining factor in the endemic 
distribution of goiter, but that the infection of the water supply is. The distribution 
of goiter in the mountainous southern portion of Bavaria, as well as in Switzerland, 
they consider to be due to certain conditions depending upon the mountains themselves 
and not their geological formation as such. 
McCarrison in his analysis of conditions in the goitrous regions of Chitral and Gilgit 
in Northern India finds that the water supply of the Chitral district comes from meta- 
morphic rocks consisting mainly of gneiss and slate and to a lesser extent of limestone. 
There are, however, certain large outcrops of limestone, and it is from these that the 
most goitrous villages derive their water supplies. Likewise the highly goitrous villages 
of Gilgit are supplied by water from a valley which contains a considerable outcrop of 
limestone. These results are likewise at variance with the theory of Bircher concerning 
the influence of geological formation. 
Dieterle (1913) after a personal examination of a series of goitrous localities in 
Switzerland comes to the conclusion that neither the geologic formation upon which 
