SYNCHRONIZED GROWTH IN TETRAHYMENA CELLS 



149 



in which the washed cells are incubated at various times with DL 

 p-fluorophenylalanine in concentrations which cover a range of 10,000 

 ( 5.5 X 10-^ to 5.5 X 10^ M ) . Figure 10 shows the division maxima as 



l.Or 





2 3 



hours after EH 



Figure 10. Delays of the first synchronous division (washed cells) by 

 p-fluorophenylalanine. In the strongest concentration, 5.5 x IQ-^ M (•), there 

 is no division when the continuous exposure starts at 0, 9, or 24 minutes after 

 E.H. There is delay when the exposure begins at 37 minutes, but no delay 

 when the cells are exposed at 53 and 65 minutes after E.H. The other con- 

 centrations are 5.5 x IQ-^ M (x); 5.5 x lO-^ M (A); 5.5 x IQ-^ M (o); 5.5 x 

 10-8 M ^|-|^ ^Yhe controls are marked -f . 



