Measurement of Rate of Shrinkage of Turgid Tissues . I. 307 
the cell-sap and of the bath of cane-sugar), at that time the ratios of the 
amounts of contraction would be significant, but as these initially equal 
forces die away quickly where the curve is steep, and slowly where it slopes 
gently, they henceforth have all different forces at any point of time, and 
the effect of such vertical comparisons becomes more and more remote from 
any significance as time proceeds. It is obvious that at twenty-four hours 
the vertical comparison would indicate the same contraction for all 
temperatures of 12° C. and upwards. 
Fig. 17. Course of plasmolysis of elder pith in 0*731 grin. M. saccharose solution at different 
temperatures : the data taken from F. van Rysselberghe’s table. The ordinates are actual 
lengths in mm. 
To extract the real temperature relation from such a set of curves 
a horizontal section must be made through the curves, and comparison 
thus made of relative rates, because where any one horizontal line cuts each 
curve there the force at work is equal throughout the set. 
Tangents measured at these points will give a true index of the effects 
of the respective temperatures. Such treatment must give a different 
picture of the temperature effect from that presented by van Rysselberghe. 
The data on the time-relations of deplasmolysis are curiously imperfect 
and difficult to analyse. The conclusions drawn from them suffer from the 
same defect as those on plasmolysis. It becomes therefore clear that 
van Rysselberghe’s conclusions lack any precise experimental foundation. 
There is a further disturbing matter that shows itself very clearly when 
these data are presented in a graphic form. It is thereby made obvious that 
