320 Diseases of Puidtry 



very malignant and appear in many organs of the body and 

 frequently cause emaciation and death. All three of the 

 chicken tumors which Rous and his colleagues have found 

 capable of transference to other individuals belong to this 

 group. Tumors of this group are usually covered with a 

 hard, tough, fibrous tissue. 



The next group of tumors are those of the epithelial type. 

 As in the preceding group, these tumors are further classified 

 according to the particular type of body tissue they resemble. 

 Two types of these epithelial tumors have been described in 

 the domestic fowl. 



1. Adenoma (tumors with a gland-like structure). 



2. Carcinoma (cancer — epithelial cells developing in 

 epithelial tissue). 



Pickens ^ has described an adenoma of the bile ducts in the 

 domestic fowl (Fig. 72). This tumor was evidently of a 

 highly malignant type as it had been transferred from the 

 liver to the proventriculus, gizzard, spleen, intestines and 

 peritoneum. The growths were small lobulated masses, 

 the larger ones contained small cysts (sacs filled with serous 

 liquid). The abdominal cavity contained about a pint of 

 this liquid. 



Pick " and Koch ^ have each described a carcinoma found 

 in the mouth of a fowl and Ehrenreich ^ considered that five of 

 the seven malignant tumors he studied were carcinomata. 

 Three types of carcinoma have been described : squamous 

 celled, alveolar and granular cancer. Tumors of this class 

 are malignant. 



1 Pickens, E. M., "A Cysto-adenoma in a Fowl." Rept. of 

 New York State Veterinary College, pp. 261-268, 1913-1914. 



2 Pick, L., "Zur Frage von Vorkommen des Carcinoms bei Vogeln : 

 Grossen Plattenepithelkrebs des Mundhohlenbodens dei einem 

 Hiihn." Berliner klin. Wochenschr., 29, 669, 1903. 



'Koch, M., "Geschwiilste bei Tieren." Verhandl. der deutsch. 

 Geselhch. f. Path., 136, 1904 ^ Loc. cit. 



