1912.] Reaction to Transplanted Cancer in the Rat. 199 



cells may in some cases be able to recover and continue their proliferation 

 for a time. Beyond reasonable doubt, however, nearly all of the introduced 

 stroma perishes within the first few days, so that the framework of the new 

 tumour is entirely, or almost entirely, the product of the host. This view 

 coincides with that of ilexner and Jobling, who have expressed the opinion 

 that only the epithelial cells of this growth survive transplantation, that the 

 new tumour is the result of their proliferation, and that its stroma is 

 furnished by the connective tissues of the host. 



There is little need to insist upon the contrast between the condition just 

 described and that represented in fig. 2, which reproduces a graft taken from 



Fig. 2.— Flexner-Jobling adeno-carcinoma. Graft in immune rat 72 hours after implantation. The graft is 

 still separated from the host tissues by a cleft and layers of fibrin. No entrance of new blood vessels or 

 fibroblasts from the host. Parenchymal cells at surface of graft still well preserved, connective tissues 

 glassy and degenerated. Sorrel, iron alum hematoxylin, x 410. 



an immune rat 72 hours after inoculation. The outlying cells of the 

 parenchyma are still well preserved at this period, and division figures are 

 not infrequent, but there is no trace of acinous arrangement, and the cells lie 

 either as irregular groups within the lacuna? of the stroma, or else in single 

 layers at the edges of the cleft. The imbedded fragment is shrunken, it 

 remains entirely separated by a space and a barrier of fibrin from the 



