CARCINOMA OP THE THYROID IN SALMONOID FISHES. 495 



individuals who boiled the water and freed it from the precipitate which it contained 

 and added thereto wine and sugar very rarely developed goiter. Another striking 

 example of the same kind is that of McClelland (1835) relative to an endemic of goiter 

 in Deoba, India. In this locality the entire population with the exception of the 

 Brahmins had goiter. This higher caste drew their drinking water from a widely distant 

 spring. One or two other castes which had partial access to this source numbered a 

 considerable percentage of goiter cases, and the lowest caste, the Domes, drew their 

 entire water supply from a goitrous well and almost every individual had goiter. The 

 middle caste, Ragpoots, which received partly good and partly infected water from the 

 well were infected to the extent of two-thirds of the individuals. These examples are 

 but one or two from many in the literature. Those who desire to multiply such reports 

 are referred to Hirsch's Handbuch der historisch-geographischen Pathologic (2. Stuttgart 

 1883, bd. 2, p. 83), and Ewald's excellent work on Die Erkrankungen der Schilddriise, 

 Myxodem und Kretinismus, in Nothnagel's Handbuch der speziellen Pathologie und 

 Therapie (2. aufl., Wien 1909, bd. 22). 



It is clear both from recorded incidence in man and from experiments both 

 with man and animals that goiter is usually acquired through the drinking water. It 

 has been shown that from the water sources from which man acquires goiter, dogs and 

 rats may be made to develop it. We have shown that with water in which fish develop 

 carcinoma of the thyroid, diffuse parenchymatous enlargement of the thyroid in both 

 dogs and rats may be produced. From these facts inferences may be drawn that there 

 is every reason to believe that human beings also would acquire thyroid disease from 

 the use of such water. 



POSSIBLE CARRIERS. 



In a disease like carcinoma of the thyroid in the Salmonidae, which is not trans- 

 mitted directly from individual to individual but which is transmitted, if at all, from 

 the infected to the healthy by some roundabout method, the idea of carriers for the 

 agent which we believe to be the cause of the disease is very natural. Of the recent 

 experimenters with goiter water, Bircher, as a result of filtration experiments, for 

 some time advocated the view that the agent of goiter was a colloidal toxin, probably 

 liberated by some parasite incapable of passing the Berkefeld filter. The residues 

 scraped from such filters produced in young animals very profound nutritional changes 

 comparable to cretinism. The filterable factor which produces the nodular adenoma - 

 tous form of goiter, as well as the parenchymatous hyperplastic, will not pass through 

 the membrane of a dialyzer, but the residue upon the dialyzer membrane proved to be 

 particularly active. These observations have led Bircher to the belief that the agent 

 is a colloid, but he recognizes that it may also be a filterable microorganism; or that 

 if the organism itself does not pass the filter it is still the probable source of a filterable 

 toxin. 



Many authors have held that endemic goiter is certainly an infectious disease, 

 Ewald being one of the strongest advocates of this theory, and McCarrison holds the 

 same view. Schittenhelm and Weichardt (1912) consider it an infectious disease and 



