To show that sunlight is necessary for starch-making by 

 leaves. Leaf 7 had a paper label stuck to its upper surface a 

 couple of hours while the plant was exposed to sunlight ; 8 is 

 the same leaf after the chlorophyl was taken out, and 9 repre- 

 sents it after treatment with iodine. The leaf turned purple 

 in all parts except the part that was shaded by the label. 

 Starch ^as removed from the portion under the label, but was 

 not renewed because the label kept out the necessary sunlight. 

 (Drawings by M. E. Feltham.) 



II 12 



FIG. 64. 



To show that chlorophyl is necessary for starch formation 

 in the leaf. 10 is a variegated leaf from a silver-leaved geran- 

 ium ; the center is an irregular patch of green, with an irregu- 

 lar border of white, n, after taking out the green. 12. after 

 iodine treatment, the leaf turns purple only where it was 

 originally green, showing that no starch forms in the white 

 border. (Drawings by M. E. Feltham.) 



