THE CHEMICAL MECHANISM OF REGEiNERAÏlON 



11 



weights can give accurate results. In the foUowing three sets 

 of experiments, Tables VI and VII, Ihe niass of each set of 

 leaves was approximately the same, naniely about 28 gni. fresh 

 weight for 12 leaves. What interests us is, firsl, Lhe diffé- 

 rence in the dry weight of shoots produced in the leaves 

 without and the leaves with half stems, second, the increase in 

 the dry weight of the half stems left attached to the leaves 

 during the experiment. According to our theoiy this lalter 

 increase should beeqnal to or greater than the différence in the 

 shoot production in the Iwo leaves. Each set of experiments 

 was carried ont with 12 pairs of sister leaves. In thèse expe- 

 riments the leaf was always at the apex of the pièce of stem, 

 since it was found that the leaf sends its material into the 

 basai part of the stem attached lo il. The experiments lasted 

 29 days. 



Table VI. 



Table VII gives the increase in weigt in the half stems 

 during the experiment. 



We see from Table VI that the 2 cm. stems reduced the 

 shoot production in the leaves by 0,1238 gm. (dry weight). 

 Table VII shows that the stems gained in the same time 

 0,24i8 gm. in dry weight. Since this gain could hâve no 

 other source than the supply of material from the leaf, the 

 experiments make it probable that the suppression of shoot 

 production in the leaf is caused hy the absorption of material 

 from the leaf by the stem. In experiment II the stems were 

 twice as long as in experiment I and hencew^e notice that thèse 



