34 



REGENERATION 



the petiole of the leaf may have created a slight obstacle for the 

 sap flow into the stem. In any case, we shall see that if the 

 half stem is not mutilated in this way its gain in dry weight 

 exceeds slightly the difference in the dry weight of shoots and 

 roots produced in the detached leaf and its sister leaf attached to 

 a stem. Since the gain in the mass of the stem must have 

 occurred in this experiment through material furnished by the 

 leaf, the inhibitory influence of the stem on the regeneration in 

 the leaf is within the limits of accuracy of the experiments 

 accounted for by the flow of material from the leaf into the stem. 

 On account of the fundamental character of these experiments 

 the results of 5 similar sets of experiments are given in Tables X 

 and XI. The 5 sets of experiments were made each with 12 

 pairs of sister leaves, and in these experiments the axillary bud 

 was not cut out. In Table X is given the dry weight of the half 

 stem at the beginning and the end of the experiment. The last 

 vertical column gives the increase of the dry weight of the half 

 stem connected with the leaf. 



Table X. — Dry Weight of Half Stems at Beginning and End of 



Experiment 



This increase in the dry weight of material of the half stems 

 connected with the leaf (which included shoots formed in the 

 pieces of stem) should be equal to or larger than the mass of 

 shoots formed in the detached leaves (Table XI) if the inhibitory 

 action of the stem on root and shoot formation is due to the fact 

 that the material available for root and shoot formation in the 

 detached leaves flowed into the stem. The dry weight of roots 



