80 On the Reproduction of Buds. 



have drawn in a former paper*, which the facts (though 

 quite correctly stated) do not, on subsequent repetition of 

 the experiment, appear to justify. I have Stated, that when 

 a perpendicular shoot of the vine was inverted to a depend- 

 ing position, and a portion of its bark between two circular 

 incisions round the stem removed, much more new wood 

 was generated on the lower lip of the wound, become upper- 

 most bv the inverted position of the branch, than on the 

 opposite lip, which would not have happened had the branch 

 continued to grow erect ; and I have inferred that this effect 

 was produced by sap which had descended by gravitation 

 from the leaves above. But the branch was, as I have there 

 stated, employed as a layer, and the matter which would 

 have accumulated on the opposite lip of the wound had been 

 employed in the formation of roots, a circumstance which 

 at that time escaped my attention. The effects of gravitation 

 on the motion of the descending sap, and consequent growth 

 of plants, are, I am well satisfied, from a great variety of 

 experiments, very great; but it will be very difficult to dis- 

 cover any method by which the extent of its operation can 

 be accurately ascertained, For the vessels which convey 

 and impel t the true sap, or fluid from which the new wood 

 appears to be generated, pass innned lately from the leaf-stalk 

 towards the root ; and though the motion of this fluid may 

 be impeded by gravitation, and it be even again returned 

 into the leaf, no portion of it, unless it had been extravasated, 

 could have descended to the part from which the bark was . 

 taken off in the experiment I have described. I am not sen- 

 sible that in thediflerent papers which I have had the honour 

 to address to you, I have drawn any other inference which 

 the facts, on repetition of the experiments, do not appear 

 capable of supporting. 



I am, &c. 



'J HO 

 *■ Phil. Trans, of 1803. + Phil, Trans, of 1804. 



Elton, 'J HOMAS ANDREW KnIGIIT. 



May 12, 1805. 



XVI. Pro- 



