CARCINOMA OF THE THYROID IN SALMONOID FISHES. 369 



The excellent plates in color and most of the other drawings are the work of Miss 

 E. S. Carrington, of Louisville, Ky. 



Dr. F. W. Baeslack, formerly of the Gratwick Laboratory, autopsied a portion of 

 the tumor-fish material. Of the present force of the laboratory the work of Mr. Damon 

 Averill deser\'es special mention. He has had to do with the fish material from the 

 beginning of the investigation, has done a part of the histological work and all the 

 extensive photography involved; to the photomicrographs particularly, on which the 

 value of this report largely depends, he has devoted much pains and skill. 



Miss C. A. Maclay, secretary of the State Institute, has had charge of many details 

 concerned in the investigation, has prepared much of the manuscript for the printer, 

 and taken part in the proof reading. 



The translations of the summary and conclusions into German and French we owe to 

 the skill of Dr. Max Breuer and Dr. Charles van Bergen , both of Buffalo. 



HISTORY OF THE DISEASE. 



The existence of this disease was first noted in 1883 by a German investigator, 

 R. Bonnet, who published in the Bavarian Fisheries Journal the description of a peculiar 

 epidemic occurring among the lake trout {Trutta lacustris) at the fish hatchery in Torbole 

 on the Gardasee, and, between the middle of February and the end of June, killing no 

 less than 3,000 fish. All of these fish had tumors at the junction of the gills. 



Bonnet did not recognize that this disease was cancerous in its nature. The first 

 to recognize the tumor as carcinoma was Scott (1891). The full text of his " Note on the 

 Occurrence of Cancer in Fish" is as follows: 



The fish afflicted with this disease were all specimens of the American brook trout (Salmo fonlinalis) 

 kept in confinement in one of the ponds at Opoho belonging to the Dunedln Acclimatization Society. 

 Males and females were alike affected and the diseased fish never recovered. Through the kindness 

 of Mr. Deans, the manager, I was able to examine several specimens showing the disease in various 

 stages of advancement, and the following is a short account of the naked-eye and microscopic appear- 

 ances of the growth. 



In the earliest stages the ventral wall of the pharynx in the middle line, a short distance behind 

 the tongue, is seen to be somewhat roughened and raised in low irregular swellings. At this stage 

 nothing is to be seen imless the mouth is opened widely. As the tumor grows, however, not only does 

 it involve more and more of the pharyngeal floor, spreading also to a slight extent laterally, and involving 

 the ventral ends of the gill arches, but it ultimately shows itself externally as a rounded pink lump 

 on the isthmus in the angle between the diverging branchiostegal rays. 



A microscopic section of the tumor shows all the stages in the development of a carcinomatous 

 growth. In parts a purely glandular structure is seen — the glands, apparently, of the acinotubular 

 type. Elsewhere, owing to the proliferation of the cells, the gland acini have become distended and 

 irregular in form (adenoma stage), while in large areas these overdistended acini have burst, as it 

 were, and the liberated cells, making their way into the stroma, infiltrate it, and all gland structure is 

 lost (carcinoma stage). 



Of the two figures which accompany this note, the first (Fig. i) shows the floor of the mouth and 

 pharynx, as seen from above, of a fish suffering from the disease. The nodular character of the tumor 

 is clearly seen . The second shows a small portion of a section as seen under the microscope. A distended 

 acinus is seen liberating a stream of cells into the gland stroma (Fig. 2). 



