CARCINOMA OF THE THYROID IN SALMONOID FISHES. 4I I 



OCCURRENCE OF THE DISEASE UNDER WILD CONDITIONS. 



It is through the domestication of trout that attention was first attracted to thyroid 

 disease in fish, and it is from this source that nearly all material and data have been 

 derived, both in this country and in Europe. Nevertheless, the same thyroid process 

 has been identified with certainty among adult fish living in open natural waters. 



The most important example of the kind at hand is a whitefish from Lake Keuka, 

 N. Y. This fish, of which the head alone came to our hands, is a member of the genus 

 Coregonus of the Salmonidae and belongs probably to the common species of whitefish 

 of Lake Keuka, Coregonus dupeiformis . (Fig. 67.) It was reported as about 60 

 centimeters in length, probably a female, though the sex was not definitely determined, 

 was caught December 3, 1909, in water about 15 meters deep, and was preserved in 

 formalin about two days later. The tumor, which is described in detail below, is of good 

 size and shows the typical structure common to this growth in the other salmonoid 

 species considered. 



From the museum of the University of Buffalo has come to us a brook trout (S. 

 fontinalis) having a large thyroid tumor. (Fig. 69.) The fish (diagram 23, p. 30) is a 

 female 17 centimeters in length and was caught by Prof. Herbert M. Hill in 1902 from 

 Hosmers Creek, near Sardinia, Erie County, N. Y. About 3 miles of this stream con- 

 stituted a fishing preserv^e of the nature of a wild stream. It had for several years 

 prior to this time been stocked with 5,000 to 10,000 fingerling trout, all obtained from 

 the New York State Hatchery at Caledonia, N. Y. Some fry of the same species were 

 also obtained from the same source and were kept in a pond adjacent to the creek 

 where they were reared to fingerling size and then liberated in the creek. No artificial 

 feeding of any kind was done in the stream and the fish in question was either planted as a 

 fingerling, or possibly as fry from the Caledonia hatchery, or was possibly a descendent 

 of some few wild fish which occupied the stream before systematic stocking was com- 

 menced. It is more probable that the fish was originally a fingerling sent from Cale- 

 donia. From its size it was probably not under 2 years of age. 



The tumor occurring in the wild living whitefish is found on inspection to pro- 

 trude in both gill spaces and between the first and second gill arches in the floor of 

 the mouth. It infiltrates the structures below the floor of the mouth beneath the 

 first and second branchial arches. (See diagram i6, p. 28, and fig. 67.) Under the 

 microscope the tumor presents areas of vesicular type. The alveoli are small, but 

 few of them contain stainable colloid. The bulk of the tumor is made up of areas of 

 closely packed deeply staining islands of cells, presenting the merest suggestion of alveolar 

 structure. The cells are closely packed, the nuclei vesicular, the protoplasm deeply 

 staining. Throughout the tumor there are evidences of karyorrhexis. The tissue 

 presents the appearance of not having been freshly preserved, but the histological 

 characteristics are sufficiently discernible. The nuclei are vesicular, and nucleoli 

 and karyokinetic figures are quite frequent. In some areas the cells are so closely 

 packed as to present the appearance of spindle-celled tissue. The whole presents the 

 characteristic picture of small alveolar carcinoma. The infiltrative characteristics 



