DIGESTIVE ACTIVITY OF MESENCHYME 453 



Grafts of two clays' growth: 1. The growth consists of splenic 

 tissue and numerous scattered tumor cells. Some of the tumor cells 

 contain ingested chick erythrocytes and are found occasionally in 

 vacuoles surrounded by mesenchymal cells. 



2. Good growth of splenic and tumor tissue. The graft contains 

 two tumor foci surrounded by splenic mesenchyme, partly in loose 

 arrangement, partly in the form of condensed areas. Splenic reticular 

 cells are found in great numbers around the loose tumor cells in the 

 periphery of the tumor focus. Some tumor cells are encircled by 

 patches of small mesenchymal cells; they appear healthy and are 

 either in the resting stage or in mitosis, 



3. Intense growth of both tissues. The splenic and the tumor foci 

 are in proliferation. Wherever both tissues come into contact numerous 

 tumor cells are seen to be encircled by mesenchymal cells. 



4. The graft as a whole did not take over the greatly thickened 

 serosa. All of the splenic tissue and most of the tumor tissue are necrotic. 

 Groups of tumor cells are found surviving and even proliferating 

 within the necrotic tissue. 



Grafts of three days' growth: 1. The graft contains two tumor 

 foci, and a considerable amount of splenic tissue. One tumor focus 

 is growing rapidly and contains innumerable mitoses. It is not com- 

 pletely surrounded by splenic tissue and a zone of marked mesenchymal 

 digestive reaction is present only where both tissues come into con- 

 tact. Another tumor focus completely surrounded by splenic mesen- 

 chyme shows a mesenchymal reaction on its whole periphery. Tumor 

 cells in mitosis are seen encircled by mesenchymal cells. 



2. Both tissues in the graft are well intermingled and are in intense' 

 proliferation. There are a great number of tumor cells in the resting 

 stage as well as in different stages of mitoses closely surrounded by 

 mesenchymal cells. 



3. In this graft the tumor tissue is more abundant than the splenic 

 tissue. Mitoses of tumor cells are very abundant. There is a marked 

 phagocytic reaction wherever both tissues are found in contact. 



4. Two foci of growing tumor are found in the graft. Both are 

 surrounded by the splenic mesenchj^mal syncytium and the process 

 of gradual tumor cell destruction within the mesenchymal capsules is 

 very active. 



Grafts of four days' growth: 1. There is a good-sized tumor focus 

 in the midst of intensely growing splenic tissue. The phagocytic 

 reaction is very strong. There are numerous spherical tumor cells in 

 vacuoles, rounded up, with ragged cytoplasm at their periphery. Various 

 phases of degeneration of tumor cells within mesenchymal capsules. 

 Some of the tumor cells, however, are in mitosis, though encircled 

 and in vacuoles; a tumor cell in prophase in a vacuole, and two tumor 

 daughter cells still connected by a cytoplasmic strand encircled by 

 mesenchyme are present. The tumor cells are extensively cut off from 

 the central part of the tumor focus which still has a healthy appearance. 



