THE CHEMICAL MEGllANISM OF HEGEiNEHATION 9 



witli their apices inlo water, both leaves may form shoots but 

 the mass of shoots produced by the two sister leaves is no 

 longer eqiial. The leaf with a stem attached will produce a 

 smaller qiiantity of shoots than the leaf withoul slem, and the 

 différence in the mass of shoots produced by the two sister 

 leaves can serve as a measure for the inhibiting' effect of Ihe 

 pièce of stem upon shoot production in the leaf. By this 

 method it was found that if the masses of leaves are equal 

 the inhibiting power of the stem increases with its size or 

 mass. Table V may serve as an example. 



Table V. 



Sixteen pairs of sister leaves were chosen, 16 leaves were 

 attached each to a (half) (1) stem 1 cm. long; the 16 sister 

 leaves had no stem attached. The latter produced in 

 17 days oo shoots weighing 2,361 gm., the former 42 shoots 

 weighing 1,677 gm. The inhibiting effect of the 1 cm. half 

 stem upon shoot production in the leaf was, therefore, 

 2,361 — 1,677 = 0,684 gm. In a parallel experiment 

 14 pairs of sister leaves weighing almost exactly as much as 

 the leaves in the first experiment were used; 14 leaves were 

 attached eacli to a half stem 6 cm. long, while the sister 

 leaves had no stem attached. The latter produced in 17 days 

 49 shoots weighing 2,6o6 gm., while the leaves with stems 

 produced only 16 shoots weighing 0,441 gm. The inhibiting 

 effect of the 6 cm. stem upon shoot production in the leaves 



(1) It will become clear later on what is meant by lialf slem. 



