662 



Microscopical Essays, 



p rived of the bark ; becaufe they have rays of the fame fubftance 

 within, which anfwer the purpofe, and this in a degree anfwering 

 to the nature of their life. 



The bark appears to be formed, firft, of longitudinal fibres, 

 which Duhamel confiders as fo many lymphatic veffels; fecond- 

 ly, by a kind of a filmy cellular tiflue, which have been confider- 

 ed as a kind of bladders by fome, or as parenchymous by others; 

 thirdly, of the vafa propria interiora, or interior juice vefTels. 



The longitudinal fibres are difpofed in ftrata, which lie one 

 over the other. In that ftratum which is next the rind, or rather 

 the cellular coat, we perceive a net of longitudinal fibres, the 

 mefhes of which are large and eafily diftinguifhed, particularly 

 when the cellular tiflue that fills up the interftices is removed. To 

 do this, the branches fhould be macerated for a confiderable 

 time ; fome require to be kept in this ftate for years. It will 

 then be eafy to feparate firft the rind, then the cellular coatings 

 and afterwards this pulpy matter. It may fometimes.be eafily re- 

 moved after the branches have been boiled. 



The mod: exterior ftratum, when examined by the naked eye, 

 •feems to be formed of Ample fibres, which graft., folder, or 

 anaftomofe one with the other ; but when examined by a micros 

 fcope, each of thefe fibres will be found to be a bundle of 

 filaments, which may be eafily feparated from each other. . 



Grew fays, that each filament, like the nerves in animals?, 

 con fills of twenty or thirty fmall contiguous tubes, which run 

 uniformly from the extremity of the root, without fending off any 



branches, 



