THE INHIBITORY ACTION OF APICAL LEAVES 



95 



merits: If all the leaves of a piece of stem less than one year old, 

 with the exception of one sufficiently large apical leaf, are 

 removed (Fig. 72) and if the bud opposite the leaf in the most 

 apical node (designated as 0) is also removed, no shoots are 

 formed in node 1 (that is, the first node below the leaf), but one 



Fig. 71. — Inhibitory action of apical leaves on shoot formation in the basal 

 part of young stems. Only roots but no shoots are formed in such cases. Oct. 

 8 to Nov. 19, 1923. 



of the buds in node 2 grows; namely, the one on that side of the 

 stem which is opposite the leaf. If this second bud is also 

 removed either a shoot grows out in the fourth node below the 

 leaf, but on the side of the stem opposite to that of the leaf, or 

 (what is more generally the case) no regeneration occurs in the 

 stem. 



These observations confirm the fact that the descending sap 

 from the leaf inhibits all shoot formation in its path, that is, 



