THICKENING OP SOME TREE STEMS. 21 



have tried it by biuding and by cutting out a ring, and in 

 both cases the inconvenience suffered by the tree has only 

 been temporary. A considerable bulging appears the first year, 

 just as in the case of the Sycamore, but special attention 

 seems to be devoted to the repair of the injury, and by the 

 end of the second year the Lime has, in all my experiments, 

 succeeded in pretty well repairing the damage to such an 

 extent as to let normal growth again proceed. In this bit of 

 a Lime stem, which measures 12i inches in circumference at 

 the middle, I cut out a spiral curve from the bark, going twice 

 round the stem, and scraped the wood well with a knife. The 

 result as now shown is that, after two years' growth, the gap 

 is quite covered over with new bast, connecting the part above 

 with that below. In the Lime tree, therefore, there appears to 

 be a recuperative power which the Sycamore has not got, and 

 for this reason it can the more easily make good any injury 

 that has been done to its bark. 



An interesting point is that, in all the stems of Sycamore 

 and Lime that I have cut, the checking of the flow of assimi- 

 lated sap has been at once followed by a great development 

 of buds from the stem at and below the region of obstruction. 

 The specimens herewith shown give evidence of this. The aim 

 of the plant and the consequent direction of its energy seem to 

 be to restore, as far as possible and with the least possible loss 

 of time, the original conditions of growth. Since the flow of 

 assimilated sap necessary to promote growth in thickness below 

 a certain level has been cut off, the next best move is to 

 develop new twigs and le&ves to provide an independent supply. 

 Below the spiral or the ring, all of the trees tried have shown 

 a large number of such buds. We know that a similar result 

 follows pruning — that when a gooseberry twig gets a part cut 

 from it, a number of branches spring out from it; or that 

 when a tree — a Chestnut, for instance — gets its leading top 

 branch broken, the consequence is the growth of many lateral 

 branches, which form a bushy top. Advantage of this principle 

 is taken in pruning a hedge of Hawthorn or Privet or Holly; 

 for one twig that is cut off two or more are developed to take 

 its place, and by this means the hedge is thickened. 



Now, from the foregoing experiments it seems to be the case 



