UPWARD TRANSPORT OF ORGANIC MATTER 



27 



almost nil. The first series of Philadelphus in Table 4 

 had only a few leaves above the ring or only a short distance 

 defohated, while the second and third series had more 

 leaves above the ring or a longer distance defohated. In 

 fact, in Series 2 and 3 the rings were made on the older 

 wood just below the base of the new shoots. Figure 3 

 shows the appearance of a representative set from Series 2. 



Fig. 3. — Effects of ringing on leafy and defoliated shoots of Philaddphus. 

 1, leafy not ringed; 2, leafy ringed; 3, defoliated not ringed; 4, defoliated ringed. 

 A black thread tied on each shoot at x indicates the position of the bud apex at 

 the time of ringing. 



It would seem that materials necessary for growth are 

 carried upward through the phloem tissues, that they 

 cannot be carried through the xylem, but that if the leaves 

 are present above the ring, they contain or can produce 

 materials that allow for considerable growth. Since leaves 

 can produce this material, the evidence seems rather 

 strong that the check in growth of the ringed defoliated 

 shoot is due to lack of carbohydrate. The check in growth, 

 it seems, cannot be due to lack of water resulting from 

 injury to the xylem for, when leaves are left above the 

 ring, growth is more nearly normal or may even exceed 

 that of the check for a short time. Occasionally, however, 

 ringing is followed by withering of the parts above the 

 ring, especially if the ring is near the tip, but this occurs 

 only when this part is defoliated. 



