4 1 8 T))-. Bell on the Phyfiohgy of Plants. 



wood. But I cannot accede to this opinion : 

 for although in the beginning, the Juccus proprius 

 flows from both margins of the incifion, in a 

 little while, as I have obferved, it is difcharged 

 froi^n the fuperior margin only. This obfervation 

 in itfelf is not however decifive. For it mav 

 be fuppofed, that the liquor flows more copioufly 

 from the fuperior margin, becaufe the preflfure 

 of the air is lefs upon it, than on the inferior, 

 and becaufe the liquor itfelf is difpofed to fall 

 downwards by its gravity, in the fame manner 

 as the /uccus communis. That I might put this 

 matter out of doubt, I placed the branch of a 

 pine in a horizontal pofition, and another 

 branch I inverted, fo that its branches were 

 turned towards the earth. In thefe fituations, 

 I cut a portion of the bark and wood from each, 

 and, in both inftances, the/uccus proprius flowed 

 only from thofe margins of the incifions which 

 ivere fartheft from the roots. Hence it appears 

 clearly, that the courfe of this juice, in its 

 veflels, is never from the roots towards the 

 branches, but always in the contrary diredion.* 



Befides the veflTels of the Juccus proprius, and 

 thofe conveying the fap, a third kind are found 



* From the experiment above recited. It appear*, that 

 the flow of the proper juice is not influenced in the fame 

 degree, as that of the fap, by an alteration in the pofl;ure 

 of the veffeL from which it iffues. To what caufe this is 

 owing does not clearly appear. J. C. 



in 



