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XXIV. Physiological Observations upon the Effects of partial 

 Decortication, or Ringing the Stems or Branches of Fruit 

 Trees. By Thomas Andrew Knight, Esq. F. R. S. $c. 

 President. 



Read June 6th, 1820. 



It has not, 1 think, been sufficiently explained by what 

 means the obstruction, or prevention, of the passage of the 

 fluids of trees through their bark operates in occasioning 

 an increased production of blossom, and a more rapid 

 growth, and more early maturity, of the fruit; the gardener 

 is, in consequence, in many cases, unable to foresee whether 

 he is likely to obtain benefit, or to sustain injury, from the 

 operation: and he is wholly without the means of knowing 

 how to adapt his mode of operating, with any degree of 

 precision, to the object which he has in view. I therefore 

 address the following observations, under the impression 

 that the hypothesis, which I have advanced in different 

 papers in the Philosophical Transactions, will afford a satis- 

 factory explanation of the cause of all the abov ementioned 

 effects. 



According to that hypothesis, the true sap of trees is 

 wholly generated in their leaves, from which it descends 

 through their bark to the extremities of their roots, depositing 

 in its course the matter which is successively added to the 

 tree; whilst whatever portion of such sap is not thus expended 

 sinks into the alburnum, and joins the ascending current, 

 to which it communicates powers, not possessed by the re- 



