THE ROLE OF THE INHIBITING EFFECT 



59 



wilted roots in the upper nodes. A few days later, it was difficult 

 to find traces of these latter roots. The polar character of the 

 regeneration as it appears ultimately is therefore a secondary 

 phenomenon. 



In a completely defoliated stem the polar character of 

 regeneration is also less pronounced at the beginning. Figure 46 

 shows the appearance of a defoliated stem after 13 days. In 

 order to accelerate regeneration the base of the stem was put into 

 water. Roots had formed at first in nodes 2, 3, 4, and 5. A 

 little later roots appeared at the extreme base dipping into 



Inaip 



Fig. 45. — The same stem as in Figs. 43 and 44 on Nov. 7. The roots at the 

 base have grown vigorously, suppressing the further growth of roots in nodes 

 1, 2, 3, and 4. These latter roots are now wilted and about to fall off. The 

 stem has now a shoot only at the apex and roots only at the base, thus exhibit- 

 ing the polar character of regeneration which did not exist in the earlier stages 

 of regeneration. 



water, and now the roots in the higher nodes began to wilt. The 

 stem is drawn in that stage (on the thirteenth day). Later the 

 wilted roots fell off. Shoots had formed not only in the most 

 apical node marked but also in the first node below; the more 

 rapid growth of the shoots in the most apical node inhibited the 

 growth of the shoots in the node below. 



The phenomena here described are not exceptions but the rule. 

 The polar character of the regeneration is not obvious from the 

 beginning, but is a secondary phenomenon and the explanation 



