Immunity of Rats towards Jensens Rat Sarcoma. 



19 



fresh reaction tissue is formed at a distance. In this way growth proceeds, 

 being always separated from the normal tissues of the host by a thin 

 capsule of vascular fibrous connective tissue. 



Summary. — The reaction tissue consists first of inflammatory oedema, 

 which subsequently subsides, and allows the tissue elements to become 



^ C S PL BV 



Fig. 12. — Shows a small portion of the margin of the inoculated material, to the left ; 

 separated by the "■ cleft " from a portion of the reaction tissue of the host, to the right ; 

 24 hours after inoculation. S, sarcoma cells outside " cleft " ; P, polymorphonuclear 

 leucocytes : BV, blood-vessels ; F, fibroblasts ; L, lymphocytes ; C, cleft. 



CD S S BV ~W ' 



9 



i 



I C : __By SO L _F FA F_ 



Fig. 13. — Shows the same structures 48 hours after inoculation. F, fibroblast ; FA, fat ; 

 M, muscle ; BV, blood-vessels ; L, lymphocyte ; S, sarcoma cell ; SD, sarcoma cell 

 dividing ; CD, cell' debris ; C, cleft. 



CD S BV F 



w 



X 



C - . i SD. BV fA 



Fig. 14. — Shows same structures 72 hours after inoculation. Letters as above. 



more closely packed. After two days the tissue consists of a vascular 

 connective tissue, through which are scattered a few lymphocytes. The 

 sarcoma cells within the cleft soon present degenerative changes, and by the 

 third day only cell-debris remains. At the end of 24 hours, healthy 

 sarcoma cells, some dividing, are seen outside the cleft ; on and after the 



c 2 



