454 VERA DANCHAKOFF 



2. The graft contains a large amount of splenic tissue in which a 

 small tumor focus is found surrounded by a large zone of mesenchymal 

 reaction. Thousands of tumor cells are found in vacuoles, greatly 

 altered in the extreme peripheral zone, better preserved toward the 

 central part of the focus. The presence of innumerable vacuoles con- 

 taining small parts of tumor cells serves as evidence that the tumor 

 growth would have been much more abundant but for the active de- 

 struction of tumor cells. In the center of the tmiior focus a few healthy 

 tumor cells are present, some of them still in mitotic division. 



3. No tumor found. Numerous patches of splenic mesench^'mal 

 cells are present. 



4. Two tumor foci within a good-sized graft of splenic tissue. One 

 of the tumor foci consists of large isolated tumor cells, practically all 

 of them encapsulated and partly digested. Granular leucocytes are 

 very abundant in this part of the graft. The second of the tumor 

 foci is separated on one side from the splenic tissue by masses of ne- 

 crotic tissue, and only in this part does the texture of the tmiior tissue 

 present a normal appearance. 



Grafts of five days' growth: 1. Graft no longer contains tumor 

 tissue. Numerous small accumulations of multicellular Plasmodia 

 representing presumably the remains of the condensed mesenchyme 

 after the tumor cells have been digested. 



2. The graft is large and contains splenic tissue only. 



3. A large graft of splenic tissue contains scanty isolated tumor cells 

 closely surrounded by mesench5Tnal syncytium, most of them greatly 

 altered. 



4. A large graft of splenic tissue, no tumor tissue is present. 

 Grafts of six days' growth: 1. No tumor tissue is present within 



a large splenic graft, there are accumulations of plasma cells in the 

 splenic tissue. 



2. A large graft of splenic tissue is found in great part necrotic. No 

 tumor tissue is present. 



3. No tumor, splenic tissue only, large graft. 



Grafts of seven days' growth: 1. Tumor tissue is present in the 

 graft, but only on a part of its circumference is there an evidence of 

 contact with the grafted splenic tissue. Here the digestion of tumor 

 cells has taken place in a most intensive way. In other parts of its 

 circumference the mesenchymal digestive reaction is present, though 

 moderate. The tumor tissue grows actively, while at least at one side 

 it has been destroyed. 



2. The graft is large; no tumor tissue is present, splenic tissue is 

 well developed. 



3. The graft is large; necrotic in the center. A part of the tissue 

 grafted is found as a necrotic mass above the ectoderm. No tumo'- 

 tissue is present in the graft. A few tumor cells, abnormal though 

 apparently alive, are found in the necrotic tissue above the ectoderm, 

 thus showing that even under unfavorable conditions the tumor cells 

 may survive seven days while all other cells around them succumb. 



