[34] 



V. Upon the causes of the premature death of parts of the Branches 

 of the Moor-park Apricot, and some other wall Fruit-Trees. 

 By Thomas Andrew Knight, Esq. Pres. F.R.S. 



Read June 2, 1835. 



Th e branches of all trees, during much the larger portion of the 

 periods in which they continue to live, are in their natural situations 

 kept in continual motion, by the action of wind upon them ; and of 

 this motion their stems and superficial roots partake, whenever the 

 gales of wind are even moderately strong : and I have shewn, in the 

 Philosophical Transactions, that the forms of all large and old trees 

 must have been much modified by this agent. The motions of the 

 circulating fluids, and sap of the tree, are also greatly influenced 

 and governed by it ; and whenever any part of the root, the stem, 

 or the branches of a tree are bent by winds, or other agents, an 

 additional quantity of alburnum is there deposited ; and the form 

 of the tree becomes necessarily well adapted to its situation, 

 whether that be exposed, or sheltered. If exposed to frequent and 

 strong agitation, its stem and branches will be short and rigid, and 

 its superficial roots will be large and strong ; and if sheltered its 

 growth will be in every part more feeble and slender. I have much 

 reason to believe, upon the evidence of subsequent experiments, 

 that the widely extended branches of large timber trees would be 

 wholly incapable of supporting their foliage when wetted with rain, 

 if the proportions of their parts were not to be extensively changed 

 and their strength greatly augmented, by the operation of winds upon 

 them during their previous growth. Exercise, therefore, appears to 

 be productive of somewhat analogous effects upon vegetable, and 



