570 



LORANDE LOSS WOODRUFF 



10 



9 

 8 

 7 

 6 

 5 

 4 

 3 

 2 



5 20 40 

 A 



5 20 40 



B 



Fig. 4 Summary of the results of the experiments plotted in figs. 2 and 3. A 

 shows the per cent gained in division rate by Paramaecium aurelia in five, twenty, 

 and forty drops of medium changed at twenty-four-hour intervals, over the divi- 

 sion rate of those in two drops changed also daily. B shows the per cent gained 

 in the division rate by P. aurelia in five, twenty, and forty drops of medium changed 

 at forty-eight-hour intervals over the division rate of those in two drops changed 

 also on alternate days. 



