CARCINOMA OP THE THYROID IN SALMONOID FISHES. 487 



and the dogs shipped to Buffalo. The three which received unboiled water from the 

 scrapings were in poor condition and one of them died just before shipment. 



Of these three puppies (dogs 16,17, an d 22) the one which died spontaneously (dog 16) 

 and one of the others (dog 17), both had plainly palpable thyroids, from one-third to 

 one-half larger than normal, in gross section, firm and red, approaching spherical instead 

 of normal fusiform shape. In both instances the two lobes were about equally enlarged. 

 The section of the thyroid of dog 16 shows outspoken evidence of hyperplasia. There 

 are no spherical or oval follicles, all the open spaces in the tissue are of irregular shape 

 due to pronounced papillary projections of the epithelial structure into their lumina. 

 Colloid is present in some of the follicles. The greater area of the section is composed of 

 small irregularly shaped follicles many of which contain no colloid; others partly filled 

 with poorly stainable colloid. Under high power the epithelium is found to be high 

 columnar, the nuclei enlarged and often vesicular with one or more nucleoli. There is 

 distinct enlargement of the capillaries in the stroma. In many areas the proliferation 

 has been so intense as to practically fill the alveolar spaces with compact masses of 

 epithelium. Occasional deposits of brown hematogenous pigment are found within 

 the alveoli. There is distinct variability in the size of the nuclei, occasional ones being 

 greatly enlarged and vesicular. Karyokinetic figures are rare. Diagnosis: Marked 

 hyperplasia with great reduction of colloid. (Fig. in, dog 17.) The histological 

 description of dog 16 applies in every way to dog 17. (Fig. 112.) Diagnosis: Marked 

 hyperplasia with great reduction of colloid. 



Puppy 22 was not operated until March 18, when the right thyroid was removed. 

 It was about normal in size, measuring 35 by 17 by 12 millimeters, and weighed 3 grams. 

 The dog weighed 7.71 kilograms. The third puppy (dog 22) presents a histological 

 condition in the thyroid similar to dogs 16 and 17. The epithelium is high columar, 

 the alveoli of irregular shape, due to plentiful papilliform processes into the lumen. 

 The larger alveoli contain poorly staining colloid. There is some variation in the differ- 

 ent portions of the section chosen for study in this case. One portion somewhat remote 

 from the more intensely hyperplastic region presents a somewhat more normal appear- 

 ance. The alveoli retain a more oval appearance, the papillary processes are smaller. 

 More colloid is present. The epithelium is, however, high columnar. The nuclei stain 

 poorly and more homogeneously than in the other regions where they are of a more 

 vesicular type. Diagnosis: Marked hyperplasia. (Fig. 115.) 



None of the controls (mother and two pups, dogs 19, 20, and 21) had palpable 

 thyroid enlargements. They were all operated in March, and the left thyroid of each 

 removed. These left lobes were normal in size and appearance and similar in size to the 

 right lobes. The mother dog (19) weighed 10.9 kilograms, the left lobe 2.4 grams; one 

 of the pups (dog 21) weighed 8.6 kilograms, its left lobe 2.05 grams, measuring 32 by 

 17 by 9 millimeters. The other puppy (dog 20, fig. 114) weighed 10 kilograms; its left 

 lobe 6.4 grams, and measured 47 by 22 by 12 millimeters. Histological examination 

 of the thyroid of the mother (dog 19) shows normal thyroid structure for a dog of this 

 age. (Fig. 116.) 



