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XVII. Upon the sujjposed Absorbent Powers of the Cellular 

 Points, or Spongioles, of the Hoots of Trees, and other Plants. 

 By Thomas Andrew Knight, Esq, F. R. S. President. 



Read May 17, 1836. 



-An opinion is very extensively, if not generally entertained, that 

 the nutriment which trees and other plants derive from the soil in 

 which they grow, is exclusively taken in by the cellular extremities 

 of their roots, which, from their texture, have been called Spongioles ; 

 and which in their organization differ from other parts of the root 

 in being totally without any alburnous or woody matter distinct 

 from bark. But it is through the alburnum alone of trees, as I 

 have proved by a great variety of experiments, and as is, I believe, 

 generally admitted, that the ascending sap, under ordinary circum- 

 stances, passes up from their roots into their branches and leaves ; 

 and as this substance does not exist in the Spongiole, my attention 

 was directed to an enquiry, whether the Spongioles possess the 

 power of transmitting fluids, and, if such power were found to exist 

 in them, through what peculiar channels such fluids pass up : and 

 as these questions are necessarily interesting, and to some extent, 

 in particular cases, may become important to the practical gardener, 

 I communicate the result of my experiments. 



Spongioles are obtainable in the most perfect state from large 

 seeds, such as those of the common or French bean, which have 

 been permitted to germinate by simply detaching them from the 

 cotyledons ; as they thus remain united to the caudex of the plant, 

 and its bud and plumule. Many of these were obtained from the 

 seeds of plants of several kinds, and subjected to various modes of 



