THE INHIBITING ACTION 



21 



whole leaf to themselves, thereby stopping the growth in the rest 

 of the notches of the leaf. Since this rule is of fundamental 

 importance in regeneration, it was necessary to furnish a quanti- 

 tative proof. 



Thirteen pairs of sister leaves were used for the experiment, 

 one leaf of each pair dipping with its apex into water while the 



In water 



InaiP 



Fig. 21. — Difference in the place of regeneration when the leaf is suspended 

 entirely in air and when its apex dips into water. 



sister leaf was suspended entirely in air. Table VII shows that 

 the mass of shoots and roots produced in the leaves dipping into 

 water was considerably greater than the mass of shoots and 

 roots produced simultaneously and under equal conditions by 

 the sister leaves suspended in air. Figure 21 shows the difference 

 in the appearance of the two leaves. 



Table VII 



