i6o THE PHYSIOLOGY OF PLANTS 



upward current is further weakened by evaporation from the 

 exposed woody tissues. 



In the cells above the excised ring of cortex the chief 

 factor in the elongation of the cells, the turgidity of the latter 

 is reduced. The elongation of the cells is lessened, and this 

 manifests itself in the reduction of the apical growth and the 

 diminished length of the internodes. The plastic material 

 which comes from the upper end of the branch accumulates 

 above the wound and causes an increase in the activity of the 

 cambium and a greater storage of reserve material. We 

 notice an increase in tbe diameter of the upper portion of the 

 branch compared with the portion below the ring-shaped cut. 



A shortening of the internodes, however, and an increase 

 in the amount of plastic and of reserve material, is the first 

 condition necessary for the formation of fruiting buds ; thus 

 by ringing the branches become productive at an earlier 

 period. Branches which have been ringed assume the autumn 

 tints at an earlier period and ripen their fruit earlier. Such 

 a hastening of the ripening is especially desirable in damp 

 autumns in the case of late varieties of vines, as the grapes 

 would in such cases often not ripen at all. The success, how- 

 ever, of ringing these plants, especially in the case of American 

 varieties and hybrids, will only be assured if a considerable 

 amount of splint-wood is also removed. For the very wide 

 vessels of the wood will conduct very considerable quantities 

 of water to the growing points, so that the growth in length 

 will scarcely seem to be reduced. In the case of vines this 

 procedure is used against the dropping of the berries. 



Ringing, however, must never be looked upon as one of the 

 regular operations in arboriculture ; it will always be an un- 

 natural treatment, which should only be used in exceptional 

 cases, as it generally entails the early death of the branch. 

 Only in those cases where the entire branch can be sacrificed 

 should one resort to ringing. For this operation does not 

 only affect the portion of the branch above the wound, which 

 easily breaks off", but the base of the shoot or branch is also 

 endangered. This latter portion receives no plastic material 

 from above, the cambium ring is therefore starved, and the buds, 

 owing to their deficient nutrition, do not form flowers and fruit. 



