CARCINOMA OF THE THYROID IN SALMONOID FISHES. 403 



junction. Figure 4, a view from above downward, shows a vegetating tumor in the 

 floor of the mouth. Figure 2 illustrates an isolated tumor in the jugular pit, and figure 

 5 a tumor in the jugular pit and one at the branchial junction. 



Pick's paper is particularly excellent in the thoroughness with which he deals with 

 the histology of these tumors. In fish i, with the large infiltrating tumor in the floor 

 of the mouth, he recognizes the variegated character of the epithelial structure, distin- 

 guishing an adenomatous portion and a follicular portion, both of which he closely 

 describes. He points out the absence of any evidence of a capsule and describes fully 

 and accurately the infiltrating character of the tumor tissue. He notes the extension 

 of the tumor in the lymph spaces of the neighboring muscular fascia, which he describes 

 as being destroyed by the infiltration. Strands of tumor cells which widen into follicles 

 invade the lymph spaces of the adventitia of the aorta. He describes the invasion and 

 breaking up of the tendon of insertion of the muscle of the isthmus. The epithelium 

 of the tumor invades the loose submucous fatty tissue, and the spaces of the dense con- 

 nective tissue and the tunica propria of the mucosa of the floor of the mouth. Not only 

 are the softer tissues invaded, but he finds that both cartilage and bone are destroyed. 

 This is accomplished by the tumor surrounding the bone growing into the various infold- 

 ings of the branchial arches and the cavities of the bone, opening up the capsule of the 

 cartilage, and invasion of the cartilage tissue proper, infiltration between the periosteum 

 and the bone, thus leading to the death of fragments of bone and the formation of 

 sequestra which through the process of decalcification and fibrillation disintegrate. 



In his description of fish 3 he shows, in figure 8, the invasion of the mucosa of the 

 floor of the mouth by papillary outgrowths which, in the instance illustrated, shows 

 the formation of small cystlike alveoli within the epithelium of the mucosa. In fish 5 

 he describes and in figure 9 illustrates the solid type of tumor; in figure 10 is shown 

 the polymorphic nature of the cells of this tumor. In fish 7 he describes portions of 

 tumor with large cystic alveoli, flattened single layer of epithelium and stainable colloid 

 (struma thyreoidea parenchymatosa colloides). In fish 8 the papillary type of growth 

 is described. 



Pick concludes that these tumors are undoubtedly infiltrating epithelial neoplasms, 

 malignant epithelioma, or in the general sense of Orth's definition, carcinoma. He 

 points out that the diffuse deposit of thyroid tissue does not necessarily become diseased 

 in toto; in fact, that it is more often affected at various points, that the growths are 

 pluri-centric. He thinks that these centers of growth originate simultaneously or at 

 different times, that they may grow more or less uniformly and that in some cases 

 outlying extensions of thyroid tissue become involved, these facts explaining the remark- 

 able variety of form of the tumors, the directions in which they infiltrate, whether 

 upward into the floor of the mouth or laterally into the gill spaces, and the fact that they 

 may be bilaterally symmetrical or unsymmetrical. 



He points out the absence of a capsule in any of the tumor fish. He recognizes 

 that several of his tumors have retained very definitely the thyroid structure and speaks 

 of these as presenting the character of parenchymatous struma, although in such tumors 

 the infiltrative character and destruction may be very great, these being tumors of 



