Fig. 6. Isolated leaves suspended injmoist air but kept in dark. Although 

 roots and shoots are formed no red pigment is noticeable. Duration of experi- 

 ment, Apr. 20 to May 13, 1919. 



i' i <\ 



Fig. 7. Leaves suspended sidewise and in a vertical plane in moist air. The 

 purple pigment collects near the notches on the lower side where roots and shoots 

 develop. The young leaves are full of this purplish pigment. It collects also on 

 the upper side of the middle rib while the lower side of the middle rib is free from 

 pigment. In the petiole pigment exists on both the lower and upper side. 



382 



