700 



PHYSIOLOGICAL BASIS OF POLARITY. II 



accelerates root formation in the notches. An enormous growth of 

 roots occurred in the watered notches. This suppressed the growth of 

 roots in the other notches of the leaf and caused the air roots already 

 formed there to shrink and dry up soon after they were formed. 



Fig. 11. Similar experiment as in Fig. 10, showing lliat roots form first at 

 lower edge of leaves suspended sidewisc. Drawn on 8th day of experiment. 



The drawing was made on the 17th day. Fig. 14 is a drawing of the 

 sister leaves, made also after 17 days. These sister leaves were not 

 dipped in water, but were suspended in moist air. Hence no special 

 acceleration of root formation took place in any part of the leaf. 



