830 



ANNUAL REGISTER, 1805. 



Tery freely, under changes of tem- 

 perature and of moisture; and the 

 motion thus produced must be iii 

 some degree commuiiicatcd to the 

 bark, should the latter substance be 

 in itself wholly inactive. I however 

 consider gravitution as the most 

 extensive and active cause of mo- 

 tion in the descending fluids of trees; 

 and I believe that from this agent 

 Tcgetable bodies, like unorganized 

 matter, generally derive, in a grea- 

 ter or less degree, the forms thuy as- 

 sume ; and probably it is necessary 

 to the existence of trees, that it 

 should be so. For if the sap passed 

 and returned as freely in the hori- 

 zontal and pendant, as in the per- 

 pendicular branch, the growth of 

 each would be equally rapid, or 

 nearly so : the liorizOntal branch 

 would then soon extend too far 

 from its point of suspension, at the 

 trunk of the tree, and thence must 

 inevitably perish, by the compound 

 ratio in which the powers of destruc- 

 tion, compared with those of pre- 

 servation, would increase. 



The principal ofliceof the hori- 

 zontal branch, in the greatest num- 

 ber of trees, is to nourish and sup- 

 port the blossoms and the fruit or 

 teed ; and as these give back little or 

 nothing to the parent tree, very 

 feeble powers alone are wanted in 

 the returning system. No power 

 at all had been fatal , and powers 

 sufficienty strong, wholly to coun- 

 teract the etfects of gravitation, had 

 probably been in a high degree 

 destructive. And it appears to me 

 by no means improbable, that the 

 formation of blossoms may, in many 

 instances, arise from the diminished 

 action of the returning system in 

 the horizontal or pendant branch. 



I have long been disposed to be- 



lieve the ascending fluids iu thef 

 alburnum and central vessels, where.* 

 ever found, to be every where the 

 same ; and that- the leaf-stalk, the 

 tendril of the'vine, the fruit-stalk, 

 and the succulent point of the an- 

 nual shoot, might in some measure 

 be substituted for each other ; and 

 experiment has proved m}' conjec- 

 ture, in many instances, to be well 

 founded. Leaves succeeded, and 

 continued to perform their office, 

 when grafted on the fruit-stalk, the 

 tendril, and succulent shoot, of the 

 vine ; and the leaf-stalk, the tendril, 

 and the fruit-stalk, alike supplied a 

 branch grafted upon them Avith 

 nourishment. But I did not succeed 

 in grafting a fruit-stalk of the vine, 

 on the leaf-stalk, the tendril, or suc- 

 culent shoot. My ill success, how- 

 ever, 1 here attribute solely to want 

 of proper mauagement ; and I hare 

 little doubt of succeeding in future. 



The young shoots of the vine, 

 «hen grafted on the leaf-stalk, often 

 grew to the length of nine or ten 

 feet ; aiul the leaf-stalk itself, to 

 some distance l>elo\v its juncture 

 with the graft, was found, in the 

 autumn, to cofltaiu a considerable 

 portion of wood, in every respect 

 similar to the alburnum in other 

 parts of the tree. 



The formation of alburnum, in 

 the leaf-stalk, seemed to point out 

 to me the means of ascertaining the 

 manner in which it is generated in 

 other instances ; and to that point 

 my attention was in consequence 

 attracted. Having grafted a great 

 many leaf-stalks with shoots of the 

 vine, I examined, in transverse sec- 

 tions, the commencement and gra- 

 dual formation of the wood. It ap- 

 peared evidently to spring from the 

 tnbles, which, iu my last paper, (to 



which 



