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Leaf Surface of Cucumis Sativus. 
Increase in Total Leaf Surface under Artificial Light. 
In Fig. 10 are represented the curves of total increase in leaf surface for 
the average plant under 2 lamps and i lamp respectively. Obviously the 
process differs from that in the case of plants under natural illumination in 
March and June, for the curves above are seen to be concave to the time 
axis, so that the leaf area is reaching a limit. It will be shown below how 
these results can be brought into line with those under natural illu- 
mination. 
