CARCINOMA OK THE THYROID IN SALMONOID FISHES. 491 



brought to BufiFalo. The material was kept cold in a thermos bottle during transporta- 

 tion, and on arrival was placed in a cheesecloth bag and immersed in a glass jar of water 

 and kept in the refrigerator. Preliminary trials were made by using this as drinking 

 water for rats on a raw-meat diet. No marked changes occurred during the first month, 

 but at four months one of six rats showed a great enlargement of the thyroid, and nearly 

 all had marked pathological changes consisting of reduction of colloid, increase in height 

 of epithelium, congestion and presence of numerous mitoses. A carefully controlled 

 experiment was now begun with the scrapings water, the diet being changed to dog bis- 

 cuit and salted lake herrings, the latter for the purpose of increasing thirst and con- 

 sumption of the water. Twenty-four rats received the scrapings water, and 12 control 

 rats received boiled water from the same source. This experiment is still in progress. 

 The results at the close of this record indicate that the rat thyroids tmdergo changes 

 similar to those in the dogs, but of a less intensive nature. Figure 120 shows a normal 

 thyroid of the rat from a control; figure 121, hypoplastic thyroid from a rat from this 

 experiment. 



In considering the above experiments, from which it will be seen that a definite 

 enlargement with diffuse proliferation of the thyroid gland may be produced in dogs 

 in a period of five months by giving them to drink the water in which suspended scrap- 

 ings from wooden troughs in which the fish kept had regularly developed carcinoma of 

 the thyroid, and that the control dogs receiving the same water boiled have in the same 

 time developed no appreciable change in the thyroid gland, it naturally becomes impor- 

 tant to determine what is the exact character of the change in the thyroid gland of the 

 experimental dogs. 



At the time, 1910, when the first experiments along these lines were made, we 

 were not aware of the experiments of Bircher and of Wilms in the production of 

 goiter in dogs and rats by giving them water to drink from goitrous wells. From the 

 various publications of E. Bircher it will be seen that in his results obtained in rats 

 (191 1 , b) he has produced, in periods varying from 9 to 18 months, distinct enlargement 

 of the thyroid, with pathological changes which he divides into two classes, viz, nodular 

 or adenomatous type and parenchymatous hyperplastic, mostly with degenerative 

 processes. In the nodular hyperplastic form he has produced typical struma nodosa, 

 which, as he points out, is a condition of the mammalian thyroid intimately associated 

 with tumor formation. The parenchymatous hyperplastic type seems to be an expres- 

 sion of a more intensive action of the goiter water, and it is to this type that the changes 

 we have produced in the thyroids of our experimental dogs more closely approximate. 

 In dog 18, in which we have the most outspoken change, we find distinctly marked degen- 

 erative changes of the protoplasm in the center of the lobe. These changes give, at 

 first glance, the impression of being due to poor fixation of the tissue or to post-mortem 

 change. 



Changes of a similar nature have been produced by de Quervain (i 904) in the thyroid 

 by the injections of toxic substances. De Quervain's studies indicate that the process 

 is intravital, and for his tumor rats Bircher takes the same position. It is of great 

 interest that Halsted, who originally (Welch, 1888) showed that by removing a part of 



