3 8 On the MOTION of 



IN our experiments, no fap could, at any time, be difcerned 

 either to afcend or defcend by the pith. It is a fubftance quite 

 unqualified for this purpofe. It contains no lymphatics } and, 

 fo far as I know, none of the peculiar fap-vefTels of any tree 

 are ever fituated in the pith * ; a fingularity which is not to be 

 found in any of the other parts of a plant. 



THE fubftance of the pith very much refembles that of the 

 cellular texture of plants, but is, notwithftanding, of a very dif- 

 ferent nature f. The cellular texture freely imbibes and tranf- 

 mits water ; but the fubftance of the pith obftinately repels it. 

 I have often feen colotired liquors rife in the bark and wood of 

 trees, efpecially in the wood of the elder, but not a particle was 

 admitted by the pith, though a fubftance, to appearance, much 

 better adapted for imbibing a fluid. All thefe circumftances 

 lead to fufpec"l, that the pith has little or no mare in fupporting 

 the wood, the bark, or the general vegetation of the tree, and 

 that its principal ufe is to aid the formation of the fruit. 



ACCORDINGLY, in the numerous fedlions of trunks and 

 branches made in the foregoing experiments, the buds were 

 constantly obferved to" be connected with, and, in a manner, 

 rooted, in the pith, by means of the diametral infer -lions |. It 

 may alfo be every where obferved, that no bud exifts upon any 

 tree, without a connection with the pith ; and that buds are al- 

 ways in greater abundance where the pith is moft copious. 



IT is fuppofed by LINNJEUS , that the pith draws the nou- 

 rimment from the bark ; but the argument he ufes in fupport 

 of this pofition does, by no means, prove it. On the contrary, 

 it rather appears from our experiments, that the pith muft draw 

 its nourifliment from the woodj becaufe, during the whole 



fpring 



* M. DU HAMEI, imagine?, that there are in the pith both iiaiffeaux frofres, and lym- 

 phatiques. 



\ M. DU HAMEL thinks, that the pith and the tlffit cellulaire are the fame fubftance.. 

 J THE radiated lines of wood, which extend from the pith to the bark. 

 J Amcen. Acad. vol. 6. p. 325. 



