SOME PRELIMINARY EXPERIMENTS 



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the stem in the internode above as well as below the leaf (a, Fig. 

 115). Regeneration occurred quantitatively as if no cortex had 

 been removed from the stem. The most apical node formed 

 shoots while the shoot formation in the most basal node was 

 inhibited. Roots were formed only at the base. That the shoot 

 formation at the apex of a was due to the ascending sap sent out 

 by the leaf is shown by the pieces b and c (Fig. 115), which had no 



Fig. 115. — Proof that both ascending and descending sap are conducted when 

 parts of cortex are removed. Oct. 26 to Nov. 15, 1923. 



leaves; h was suspended in air, and c dipped into water; both had 

 formed only tiny shoots. That the root formation at the base of 

 a was due to the descending sap from the leaf was also shown by 

 the fact that the pieces b and c had formed no roots. These 

 experiments, all of which turned out in the same way, show that 

 the ascending and descending sap from the leaf can move through 

 the stem even where the cortex is removed. Only the rate of 

 regeneration is retarded in this case. The experiment lasted from 

 Oct. 26 to Nov. 15, 1923. 



