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; Bachforelle; brown trout, yellow trout, brook trout, 



river trout, etc Salmo fario Linnaeus. 



Loch Leven trout Salmo levensis Walker. 



Seeforelle or lake trout Salmo lacustris Linnanis. 



Ombre chevalier, European charr or saibling Salvelinus salvelinus (Linnaeus). [Salve- 



linus 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 the 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 eruptive 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 



