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Results of Physiological Experiments on the Formation of Wood in 

 Plants^ made in the Royal Dublin Sociefy^s Botanic Gardens, 

 Glasnevin, between the years 1839 and 1851. By David Moore, 

 Esq.* 



It may appear remarkable in vegetable physiology, that what has 

 long been considered an axiom should now be gravely disputed by 

 one of the best physiologists of the present time. Dr. Schleiden, of 

 Jena, in his admirable work, ' Principles of Scientific Botany,' flatly 

 denies that a downward current of elaborated bark-sap either does 

 or can take place in plants, which opinion gives to the experiments 

 I propose to describe much additional interest. At the time my 

 experiments were commenced, and for several years afterwards, the 

 descent of the sap in vegetables does not appear to have been doubted, 

 the whole theory of wood-formation resting on the fact of such being 

 the case. It was, therefore, more with a view of eliciting information 

 on the latter subject, than to prove or disprove that sap circulates, as 

 it has generally been considered to do, that they were undertaken. 



Before entering into details, I shall take the liberty of very briefly 

 stating 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 state- 

 ment : — " 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 ema- 

 nated, and passes along this until it reaches the leaves ; on its return 

 from them it descends through the liber, in part passing off horizon- 

 tally 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 following 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 



* Read at the Royal Irish Academy, June 23, 1851. 



Vol. IV. 2 v 



