The SAP In TREES. 37 



particularly by M. BONNET *, to be a conclufive argument, in 

 favour of a circulation of the fap. It is fuppofed, that the fap 

 rifes from the root, by the wood of a tree, to the extremities of 

 the branches, and that from thence it returns again by the bark 

 to the root, in a circulatory manner. It is therefore concluded, 

 that the bud which terminates a branch muft be the firft that 

 breaks in the fpring, becaufe it receives the firft vifit of this re- 

 turning fap. The above experiments, however, enable us to ac- 

 count for this curious appearance in a different manner. 



WE have had frequent opportunities to remark, that the fap 

 moves with greater rapidity, and in greater plenty, in young 

 than in old wood. 



THAT inverted branches, in which the fap flows more copi- 

 oufly, than in thofe which are creel, do bud the fooneft. 



THAT young trees bud more early than thofe which are old ; 

 and that the fap runs longer in young than in old wood. 



ALL which facts evidently lead to this conclufion, That, as the 

 buds towards the extremities of branches are placed upon the 

 youngeft wood, where they receive the. moft copious flow of the 

 fap, they muft, for this reafon, fwell more early, and difclofe 

 themfelves fooner than fuch as are fituated upon older wood. 

 From the early breaking of the terminating buds upon branches, 

 no proof can, therefore, be deduced in favour of a fuppofed 

 circulation. 



6. 



THE fubtile and ingenious theory of the generation of plants, 

 given by LINN.EUS f , which is countenanced by many excellent 

 facts, is further confirmed by thefe experiments ; which ftrong- 

 ly infinuate, that the tree is rather deftined to fupport the pith, 

 than the pith the tree ; the pith, according to that theory, be- 

 ing eflentially neceflary, not fo much for the vegetation of the 

 plant, as the formation of the feeds. 



IN 



* BONNET, p. 285. 



Generatio ambigena, Amoen. Acad. vol. 



