50 



* 



that they do not receive their increment in 

 the above manner, requires no experiment 

 to determine ; for every body knows that 

 the trees acquire their increment in that 

 season of the year when the periligneum is 

 separated from the wood by th^s^p. Be- 

 sides, nothing can be more evident, than 

 that the wood is possessed of sap vessels, 

 or tubes. This can be shown by a very 



simple experiment : take a piece of a branch, 





 or the like, bark it clean, and put^ne end 



into the fire, the tubes or sap vessels being 

 contracted at that end, and the sap rarified 

 by the heat, will be seen to pass off at the 

 other end in the form of steam, or fluid, 

 according to the density of the wood. And 

 there are some, as the cane, which have 

 these tubes so large, that water will readily 

 pass through them. So that, all that their 

 experiments could determine was, that the 



