FIG. 3 — Showing ciioumlier leaf with absence of starch formation where 

 cork was pinned. Note also the effect of the shadow of the cork on the forma- 

 tion of starch. 



FIG. 4 — Showing results of starch production under single and double 

 panes of glass. The darker leaves in 1 and 2 showing more starch were ex- 

 l)osed to a single clean light of glass; the lighter leaves were exposed to two 

 unclean lights of glass. 



