102 
Gregory. — The Increase in Area of Leaves and 
the time corresponding with the point of inflexion in the S curve, and would 
fall off on either side. 
Fig. 5; Curve of increase in area of third leaf, June 191 7. Equation of curve of closest fit : 
logic 
236 
23 6 — x 
= 0*200 (7 — 9.46). 
F. The Increase in Total Leaf Surface in the Greenhouse. 
The vital importance of the increase in leaf surface in the economy of 
the plant is evident from the following consideration : The total dry weight 
