ii 6 Gregory . — The Increase in Area of Leaves and 
plotting the logarithms of the areas against time the curve obtained deviates 
rapidly from a straight line. By plotting the log areas against log time, 
however, a straight line is again obtained (Fig. 14). 
Here, then, we are not dealing with a compound interest phenomenon of 
the same type as before, but the expression of the course of this phenomenon 
is of the form 
A = ae r l °s * = af. 
(12) 
