32 MASS. EXPERIMENT STATION BULLETIN 391 



were round, ov^al, or polyhedral and possessed a relatively large vesicular nucleus 

 in many of which nucleoli could be distinguished. The polymorphous cells were 

 supported by a well-developed framework of anastomosing reticulum cells similar 

 to those seen in a normal thymus. Scattered throughout the tumor were peculiar 

 large cells with an opaque acidophilic cytoplasm and relatively small vesicular 

 nuclei. Their appearance was that of giant cells, although multinucleated forms 

 could not be found. In a few places the reticular stroma cells clumped them- 

 selves together in such a manner as to suggest an attempt to form a structure 

 like a Hassell's corpuscle. 



Although the tumor was well supported by fibroblasts, it was not confined 

 by a capsule. It readily infiltrated the adjacent soft tissues including the mus- 

 culature. The muscles of the trachea were infiltrated but the annular cartilages 

 seemed to be an effective barrier to further invasion of the structure. 



2. T 306. A very fat year-and-a-half-old hen was found dead. Death was 

 apparently due to hermorrhage from rupture of the liver capsule, the cause of 

 which could not be determined. A tumor mass was found in the right jugular 

 furrow in the mid-cervical region and was apparenth' derived from the thymic 

 node of that location. The tumor measured 3X ^ X 2.5 cm., was reddish gray- 

 white in color, and was relativeh' firm. On cross section, small cysts filled with 

 clear fluid were noted. Other nodes of the thymic chain were fairly well de- 

 veloped and a representative node anterior to the tumor measured 10 X 5 X 2 

 mm. No other significant pathology was found. The histology of the tumor 

 was similar to that described in the first case (Plate IX, Figure 2). The cyst-like 

 structures were interpreted as obstructed and distended hmph channels. 



A thymoma of the chicken has been described by Feldman (6) and the two 

 cases above seem very similar to his. These tumors of the chicken show a gran- 

 ulomatous character coupled with the invasiveness of a neoplasm, which leads 

 to the question of whether or not they should be considered as a neoplasm. 

 Ewing (5) discusses this question uith regard to thymomas ol man and comes to 

 the conclusion that they should be regarded as infectious granulomas. 



Hemangioma 



Neoplasia classified as hemangionia was found in five instances. The t\pe 

 cell of a hemangioma is the angioblast, whiih teiuls to lorm new blood spaces 

 or channels. Sometimes the channels formed b\- the tumor are ol capillary size 

 and the term "capillary hemangioma" is descriptive. At other times the tumor 

 tends to form large blood spaces, for which condition the term "cavernous heman- 

 gioma" is used. Some authors favor the term "hemangio-endothelioma" in pref- 

 erence to hemangioma (Feldman 7). Both capillary and cavernous forms of 

 hemangioma were found in this collection. Although certain data on the cases 

 are presented in Table 16, a brief description of each will provide a better con- 

 ception of the cases. 



1. Case 444. Some details of this case have been described previously 

 (Olson 23). The chicken was found dead in its pen. Examination of the blood 

 made 46 days previously had shown no significant changes. A slight relative 

 eosinophilia was noted 39 da\s previous to death; and 25 da>s preceding death a 

 moderate, relative, heterophil leukocytosis was observed. A swelling of the 

 left foot pad was noted about a week before the bird died, and on the day before 

 death the chicken was wealc, dull, and listless. The carcass was emaciated. The 

 swelling of the left foot pad was soft and fluctuating and on section was found to 

 be composed of clotted blood and what appeared upon gross examination to be 

 granulation tissue. The liver was slightly swollen, was red brown in color, and 

 contained numerous foci of clotted blood under the capsule and deep in the sub- 

 stance of the organ. Similar foci of accunmlated blood were present in the kidneys, 

 lungs, heart, and spleen. The spleen was enlarged (2 cm. diameter) and consisted 

 principally of an ancient blood clot. Splenic tissue was confined to a narrow 

 crescentic border along one edge of the mass representing the spleen. The foci 

 of blood in the heart muscle and in the kidney seemed to have a thin though 

 distinct surrounding membrane. The blood in the heart chambers was not 

 clotted. No pathological changes could be noted in a smear prepared from the 



