J "cT" 



M. 



\ 



°*o 



(.^- 



O 





o 



a 



NM y 



Plate II • 



No. 3 Mouse spleen cell in culture to illustrate vacuole formation at an 

 undulating cell margin X 2000 (reduction 3/4). The interval between 

 (o) and (b) is approximately 40 seconds. The same group of vacuoles is 

 seen in both. {Continued on opposite page.) 



