128 



REGENERATION 



first retards shoot formation more than a small leaf; a stem with- 

 out a leaf is altogether free from this inhibition to shoot forma- 

 tion. 



Figure 103 was drawn 13 days later. In the meantime the 

 result was completely changed. The stems with a whole leaf 



Fig. 103. — Same stems as in Fig. 102, 13 days later, May 23. 



a larger shoot than c. 



a has now formed 



a had not only formed a shoot (in the second node basally from 

 the leaf and on the opposite side of the stem) but this shoot had 

 grown so rapidly that it at least equalled the shoot in stem h, 

 and probably exceeded in mass the two shoots in stem c. 



Six days later, that is, on the thirty-fourth day of the experi- 

 ment, the condition was that given in Fig. 104, namely the mass of 



Fig. 104. — Same stems as in Fig. 102, 19 days later, May 29. 



than in h. 



Shoot in a greater 



shoots formed in the three sets of stems varied with the mass of 

 the apical leaf. The stems a with the largest leaf had the largest 

 shoot, while the stem without leaf had the smallest shoots. The 

 inhibitory effect of the apical leaf existed therefore only at the 

 beginning of the experiment; when the experiment continued long 

 enough the mass law was established again. This was not only 



