UPWARD TRANSPORT OF ORGANIC MATTER 15 



the water through the xylem. He does not state whether 

 the felled trees that retained starch were cut early in the 

 season or late or at what season they were examined for 

 starch, nor does he state the relative number of stumps that 

 retained or lost their carbohydrate stores. 



Since other experiments have given very definite mdica- 

 tions that normally the stored carbohydrates do not move 

 through the xylem longitudinally and since in Hartig's 

 experiments the disappearance of the carbohydrates below 

 the ring may have been due to their utilization by the tissues 

 below the ring, a number of experiments were carried out 

 in which two rings were made in the same stem, one to 

 prevent upward movement, and a second at a distance 

 below this first ring to prevent movement back to the roots 

 or other parts. 



Hundreds of stems of many sizes and ages were double- 

 ringed in this way and they all showed similar results. 

 It will be sufficient here to present the results from two 

 such experiments. Pairs of stems of Ostrya virginiana 

 were selected for experiments in double ringing. The 

 stems formed arms of forks and one arm of each was 

 ringed on Apr. 6, 1919. On May 6 the shoots were begin- 

 ning growth on all the branches. No differences between 

 ringed and unringed stems were apparent. By May 19 

 the shoots of the check stems showed considerable addi- 

 tional growth but those of the ringed stems had made no 

 appreciable growth beyond that of May 6. Stems cut 

 at this time showed the following results: 



Above the Ring. — No trace of starch was present in any 

 part either in the young twigs or in the older parts of the 

 stem. 



Between the Two Rings. — Starch was very abundant in 

 the pith, medullary rays, and cortex. 



Below the Lower Ring. — The pith only contained traces 

 of starch, none being present in the medullary rays or 

 cortex. 



In the check stem which formed the other arm of the fork 

 traces of starch were present in the pith only in each of the 



