OSMOTIC EQUILIBRIUM 93 



Dixon and Atkins (loc. cit.) are of course mean values, for 

 the sap of millions of cells was taken for each freezing- 

 point determination. 



Culture experiments in 15 per cent, glycerol made up 

 with Lindner's solution showed that the number of yeast 

 cells approximately doubled itself in two days. When, 

 however, the cells used to sow this solution had themselves 

 been in it for some days, it was found that their increase 

 was much more rapid. Thus after four days' treatment 

 the number sown afresh increased to 4-3 times their original 

 number, as against 2-0 times without treatment. This 

 curious result is probably due to the much larger number 

 of young cells in 15 per cent, glycerol solution, for old cells 

 are plasmolyzed by this concentration. 



Furthermore, Euler and Palm obtained evidence that, 

 when yeast cells cultivated for twelve hours in Lindner's 

 solution containing 5 per cent, glycerol are subsequently 

 placed in 25 per cent, glycerol, the curve obtained by plot- 

 ting percentages of cells plasmolyzed, against time in 

 hours, is of a logarithmic nature as shown in Fig. 6. The 

 results are tabulated here. 



TABLE XXVII. 



Time of Experiment Percentage of Yeast Cells 



in Hours. plasmolyzed. 



1 41 



2 60 



6 78 



It was previously shown that without the preliminary 

 treatment 71 per cent, were plasmolyzed in two hours. 

 The difference between this figure and that in the above 

 table is probably due to the cells being on the whole younger 

 in this experiment, but perhaps it is in part occasioned by 

 a slight penetration of the glycerol. 



The above investigation makes it clear that, whilst it 



