Dr. Bell on the Phyftology cf Plants. ii-^"'* 



fiirrounding elements. They are chiefly nourish- 

 ed by tile water they draw from the foil ; but 

 Tomewhat they Tikewife derive from the fight 

 of the fun, on which tlieir fenfible qualities 

 principally depend. On this fubjed I have 

 likewife made fome experiments, but not with 

 that degree of exacStnefs, which fhould enable 

 me to lay them before the public. 



Some botanifls have conceived, that plants', 

 as well as animals, have a regular circCilarici^ 

 of their fluids. Others think this very im- 

 probable. On both fides, recourfe has bee^ 

 had to experiments; and from thefe, €"6^- 

 clufions perfeftly oppofite have been dedaced'. 

 When a ligature has been fixed round a tree, lA 

 fuch a manner, that no juice could be tranfl 

 mitted through the bark, the tree has been found 

 to thicken above the ligature ; hut below it, to 

 continue of the fame circumference. Hence 

 fome have concluded, that the fap afcends 

 through the wood, and defcends through thfc 

 bark. Thofe who are of a contrary opinion 

 have found, that, in certain cafes, the juice 

 afcends through the bark only : for when a 

 portion of the wood has been cut out, and 

 the bark exadly replaced, the growth of the tree 

 has been found to goon unchanged: hence ic 

 is faid, that the juice is tranfmitted equally 

 through all parts 'of vegetables. The experi- 

 ments adduced on each fide of the queftion 



are 



