188. 
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,’ &c. 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 :—‘ Y et 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 anexplanation. All that is known on the subject 
is detailed m manuals of horticulture. I will mention one 
case. Ifthe 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 slow-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. Ifa 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 
