34 On the M OTIO N of 



2. 



M. DU HAMEL *, who beftows a great deal of attention upon 

 this fubjecl, is dubious, whether the fap of trees, in the bleeding 

 feafon, be in an afcending or defcending ftate, and is felicitous 

 that the point fhould be determined by experiment. In anfwer 

 to this enquiry, it feems clear, by the above trials, that, from the 

 1 1 th of March, when the fap firfl began to run at the bottom 

 of the trunk, till the 3oth of April, when the tree began to un- 

 fold its leaves, the whole fap of the tree was in a progreffive 

 flate upwards : That it was liable, indeed, to fall back, or to run 

 out, upon incifion, in any direction ; but that, during the whole 

 bleeding feafon, there was no juft appearance of any defcend- 

 ing, returning, or circulatory fap. 



3- 



WE may next attend to the tradl obferved by the fap in its a- 

 fcent during the bleeding feafon. 



IN none of the experiments here related, could any fap be per- 

 ceived to arife, either by the pith or the bark. The whole fap 

 was conveyed upwards by the wood, and between the wood and 

 bark ; but beyond this canal, no flow of the fap could be dif- 

 cerned in any exterior part of the tree. 



IT alfo appears, that the fap moves both in the fubflance of 

 the ligneous circles, and in the veins by which they are fepa- 

 rated : That, in both, it is in an afcending ftate : That it moves 

 more expeditioufly in thefe veins than in the circles themfelves ; 

 and that it moves more freely in young than in old circles, and, 

 of courfe, more freely in the exterior than in the interior part 

 of every trunk and every branch. 



IT is afferted by Dr GREW f, and by Meffrs BONNET , LA 

 BAISSE, and Du HAMEL, that, in the bleeding feafon, all the 



fap 



* Phyfique des Arbres, torn. i. p. 66. 

 f Anatomy of Plants, Lond. 1682. fol. 

 \ BONNET fur 1'Ufage des Feuilles, p. 65. 



