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prove or disprove that sap circulates, as it has generally been 

 considered to do, they were undertaken. 



" Before entering into details, I shall take the liberty of 

 very briefly stating to the Academy the views held on this 

 important subject by Drs. Lindley and Schleiden, which are 

 entirely antagonistic. The former author, in his * Theory 

 of Horticulture,' at p. 28, makes the following statement : — 

 'When sap leaves the earth and passes into the stem, it 

 ascends by the woody matter of the finest fibres of the root ; 

 having left them, it flows into the new wood from which 

 those fibres emanated, and passes along this until it reaches 

 the leaves ; on its return from them it descends through the 

 liber, in part passing off horizontally through the medullary 

 rays. "Wherever it passes it deposits a portion of its solid 

 parts,' cfec. Dr. Schleiden, on the other hand, denies that 

 wood is formed by a descending bark-sap. In his chapter on 

 the * Reproduction of Plants,' in ' Principles of Scientific 

 Botany,' p. 535, when treating on grafting, we have the fol- 

 lowing statement : — ' Yet the stock must always exert a greater 

 or less influence on the eye or graft, as the sap brought to it 

 must pass through the cells of the stock, and become changed 

 there. In this case the relations are too complicated to enable 

 us to offer an explanation. All that is known on the subject 

 is detailed in manuals of horticulture. I will mention one 

 case. If the branch of a quick-growing plant is grafted upon 

 a very slow-growing one, as, for instance, the branch of a 

 plum upon a sloe-stock, the graft will grow rapidly, but not 

 so the stock, which retains its skw-growing character; a 

 striking example of the permanency of the specific life of the 

 stock, and, as it appears to me, affording a fatal argument 

 against the pretended descent of the sap. If a descending 

 bark-sap existed, the sloe-stock would be naturally covered 

 with annual rings of plum wood from the graft, and it would 

 grow in proportion to the growth of the graft, but this is 

 by no means the case, for the new annual rings are formed, not 



