UPWARD TRANSPORT OF ORGANIC MATTER 



23 



beginning, its deposition would not occur in any part 

 isolated by rings from a source of supply. This was 

 observed in many experiments of which the type shown in 

 Fig. 1 is a good example. In stems treated as No. 2 of 

 Fig. 1, no starch appeared in any part of the defoliated 

 region isolated by rings, even though it was very abundant 

 in the tissues above the upper ring and below the lower. 

 In stems ringed like Nos. 1 and 3, on the other hand, 

 in which the single ring prevented phloem connection 

 respectively with the leaves above only and below only, 

 there was always abundant starch in the defoliated part. 

 This starch was clearly evident in the pith, xylem paren- 

 chyma, phloem parenchyma, and cortex. Stems like No. 3 

 with the single ring at the base of the defoliated region 

 contained more starch than those like No. 1 with the single 

 ring at the top. The dry weight of the bark (everything 

 external to the cambium) together with the dry weight 

 and volume of the xylem was determined for the defoliated 

 regions. These are presented in Table 3. 



Table 3. — Effect of Number and Position of Rings on Starch Content 

 AND Dry Weight of a Defoliated Region of Stem 



No. 



Position of rings 



Ring at top only of defoli- 

 ated region 



Rings at top and bottom of 

 defoliated region 



Ring at bottom only of de- 

 foliated region 



Starch 



test 



Abundant 



Absent 



Very 

 abundant 



Dry wt. 

 per cc. of 



wood 



including 



pith 



0.74 



0.67 

 0.84 



* This was calculated from the diameters at each end of the twig and its length. In the 

 original paper the volumes given were all ten times too high as the decimal point was mis- 

 placed. The relative differences, however, were not altered. 



These data on dry weights and of the weight per unit 

 volume of these defoliated regions confirm the evidence 



