12 Society for Experimental Biology and Medicine. 



ii (154) 



Remarks on and exhibition of specimens of a metastasising 

 sarcoma of the rat. 



By SIMON FLEXNER and J. W. JOBLING. 



\From the Rockefeller Institute for Medical Research^ 



The specimens which the authors exhibited consisted of a 

 mixed cell sarcoma of the seminal vesicle of a white rat which 

 has been transplanted successfully into a series of white rats. The 

 original tumor, which was found in a rat dying spontaneously in 

 the laboratory was as large as a walnut. Its surface was covered 

 with peritoneum and its consistence was firm. Thus far it has been 

 transplanted to full-grown and young rats both by subcutaneous 

 and by intraperitoneal inoculation. The feature of the tumor which 

 we wish especially to emphasize are the large and numerous metas- 

 tases which have appeared in the inoculated rats. The rat exhibit- 

 ing the original tumor did not show visible metastases. But in the 

 animals which have succumbed after successful inoculation, the 

 metastases have been numerous and of large size. They have 

 appeared in the lungs and kidneys, and in one instance, following 

 intraperitoneal injection, in the ribs and intercostal muscles. As 

 the specimens show, the nodules in the lungs and kidneys may 

 reach large dimensions, taking in a segment of the kidney or an 

 entire lobe of the lungs. The animal in which matastases existed 

 in the intercostal muscles showed large nodules in the lungs ; in 

 this animal a growth from the lung into the pericardium, and from 

 the pericardium into the heart wall, took place. The secondary 

 tumors have the same structure as the primary tumors. They are 

 made up of spindle-shaped and polygonal cells, the latter being 

 often of large size, with lobed or irregular nuclei. Intercellular 

 substance is present, and it is in places fibrillated. 



The epicardium in the rat in which growth occurred in the 

 myocardium, showed invasion of the serosa by the sarcomatous 

 cells, spreading doubtless from the nodule mentioned and causing 

 sarcomatosis of the serous membrane. This tumor is being further 

 transplanted and studied in its biological relationships. 



