GROWTH OF ROOTS AND SHOOTS IN THE LEAF 



33 



callus formation at the basal end and for increase in thickness 

 as well as for longitudinal growth of the piece of stem (Fig. 30, 6]). 

 The data in Table IX show the inhibiting effect of the piece of 

 half stem attached to the leaf on the quantity of regeneration in 

 the leaf. 



Table IX 



Nineteen pairs of sister leaves were used in the experiment. 

 The pieces of half stem attached to one of each pair of sister 

 leaves were about 25 millimeters long. 



The total dry weight of roots and shoots regenerated by the 

 leaves with a piece of stem was 559 milligrams while that of the 

 roots and shoots regenerated by the leaves without stem was 

 1,212 milligrams. 



Hence the presence of the small piece of stem in Set I (Fig. 30) 

 diminished the quantity of regeneration in the 19 leaves of this 

 set by 653 miUigrams. (The correction for the shght difference 

 in the mass of the two sets of leaves reduced this value to about 

 630 milligrams.) 



The dry weight of the 19 half stems determined at the begin- 

 ning of the experiment was 0.747 gram. The dry weight of the 

 19 half stems (which were left in connection with the leaves) 

 determined at the end of the experiment was 1.213 grams. 

 Hence the stems connected with the leaves gained 466 milli- 

 grams which is slightly less than the excess of mass of shoots and 

 roots regenerated in the leaf without stem over that with stem, 

 namely 630 miUigrams. This difference is, however, accounted 

 for by the fact that the mass of the pieces of half stem con- 

 nected with the leaves was diminished at the beginning of the 

 experiment by cutting out the bud on the stem in the axil of the 

 leaf. To make sure that the bud was removed, part of the sur- 

 rounding tissue had also to be cut out. It is also possible that 

 in addition the mutilation of the stem near the connection with 



