CARCINOMA OF THEJ, THYROID IN SADMONOID 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 Pathologic 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 Salmonidse, 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 
