265 



illustrates how a cell, belonging to the medium-sized cell 

 type, tried to jjenetrate into a much larger cell, belonging to 

 the fibroblastic type of cell. In the fig. 70:,, 70 3, it can be 

 seen how the small active cell is pushing against the proto- 

 plasm of the big cell. After this visit, it was interesting 

 to discover if any changes were going to occur in the 

 fibroblastic cell type. The only change, which could be 

 observed, was that two vacuoles floated up to the place 

 attacked by the smaller cell. (Fig. 7O5). 



Fig. 69. 



The type of spindle-shaped cells of the Rous's sarcome 



stained with methylene blue. 



The main conclusion of these observations was, that 

 the cells, which are assumed to be the bearers of the 

 malignancy, are able to divide when isolated and scaltered. 

 This is not found to be the case with isolated and scattered 

 normal fibroblasts. The isolation and the distribution of 

 the sarcoma cells were ver}'^ easy to perform, because they 

 form loose connections with each other. Also this indicates 

 the independency of the sarcoma cells, compared with that 

 of the normal fibroblasts. 



Still more interesting is the fact, that the new cells, 

 separated from the mother cells, were generally of a much 

 smaller size than the mother cells. 



