UPWARD TRANSPORT OF ORGANIC MATTER 33 



responses and looks to factors other than those mentioned 

 above for an explanation, but it should be perfectly obvious 

 that the distribution of foods will vary with the season of 

 ringing and the position of the ring with respect to regions 

 of supply or utilization. 



Further evidence, that the failure of solutes to move up 

 past a ring is not due to lack of transpiration above, has 

 been given by Weevers (1923). By selecting branches of 

 Acer negundo or Aesculus, which bore leaves containing no 

 chlorophyll and which were therefore dependent on other 

 parts of the tree for their carbohydrates, he could study the 

 effects of ringing without resorting to defoliation. He 

 found that the ringing of such branches stopped their 

 growth and the leaves eventually withered, whereas the 

 ringing of similar branches bearing green leaves did not 

 stop their growth nor cause withering. Analyses for 

 reducing sugar showed the green leaves to contain 3 per 

 cent, the yellow leaves 1 per cent, and the yellow leaves on 

 the ringed branch only traces. The wood and bark of the 

 ringed branch bearing yellow leaves contained 6 per cent 

 starch, while that of a similar branch only partly ringed 

 contained 9 per cent starch. It is surprising, as Weevers 

 remarks, that the ringed yellow branch contained so much 

 starch while the leaves of the same branch were withering 

 and contained only traces of sugar. No mention is made 

 as to the method of determining starch or whether any 

 starch was found by the iodine test, except in the leaves 

 which showed no such test. If acid hydrolysis was used to 

 make the starch determination, it is highly probable 

 that the reducing sugars found were not produced from 

 starch but from the acid hydrolysis of hemicelluloses. 

 As reported in 1920, I found woody stems containing but 

 very slight traces of starch, as indicated by the iodine test, 

 to produce reducing sugars amounting to 17 per cent of the 

 dry weight of the wood on hydrolysis by boiling with 

 10 per cent hydrochloric acid for 2}^ hr. 



8. The Effect of Ringing on Transport to Fruits. — 

 Although the opinion has been widely held that most 



