67 



replaced a testicle. A large growth, apparently an endothelioma, 

 was found near the end of one horn of the bicomate uterus. 



METASTASES. 



Metestases have been found in a number of cases of sarcoma and 

 a smaller number of cases of the epithelial growths. Most fre- 

 quently the secondary tumors were in the Uver, the mesentery or 

 the kidney. 



Size. — In proportion to the size of the rat the tumors were quite 

 large, scarcely any under 1 centimeter in diameter having been 

 observed, and they varied from this to a growth several centimeters 

 in diameter. 



HISTOLOGICAL STRUCTUKE. 



The following tumors may be regarded as of the connective tissue 

 type: 



LIPOMATA. 



One typical lipoma has been found. It was located in the sub- 

 cutaneous tissue of the thorax and was similar in gross and micro- 

 scopical appearance to the tumors of the same nature in man. 



FIBROMATA. 



A considerable number of subcutaneous tumors have been typical 

 hard fibromas, others were fibromas in which there were a few cell 

 nests that led to the suspicion that perhaps a malignant change was 

 taking place in the tumor, or that a malignant growth was being 

 converted into one of a benign nature. 



SARCOMATA. 



Typical spindle cell sarcomas have been encountered a number of 

 times. A few round cell sarcomas were found in which there were 

 usually a number of giant cells, but hardly enough to justify one in 

 designating the growths as giant cell sarcomas. Several other 

 growths have been seen which gave the impression of being sarcomas 

 but left one in some doubt as to whether the tissue might not be of 

 the nature of a granuloma. 



Many tumors of the epithelial type were encountered which may 

 be classed together. 



ADENOMATA AND CARCINOMATA. 



Several very typical adenomas and cystic adenomas have been 

 found. A few tumors were observed that presented the appearance 

 of carcinomas. A large number of growths were observed that 

 apparently stood between the adenoma and the carcinoma and there 



