12 VITAL ACTIONS. 



tissue is very young, the spongelet {fig. 1. a) consists 



of very lax tender cellular tissue, resting upon a blunt 

 cone of woody matter, composed principally of woody 

 tubes, and connected with the alburnum* of the stem 

 (fig. 1. b) ; it is, therefore, placed in the most favour- 

 able position possible for communicating to the gene- 

 ral system of circulation the fluids taken up by its 

 highly absorbent tissue. 



23. It is the opinion of most vegetable physiolo- 

 gists, that the absorbing or feeding powers of roots 

 are conducted principally at these points ; and tbat 

 the general surface of the root possesses little or no 

 power of the kind. And, indeed, it seems highly 

 probable that this is so, when we consider that the 

 bark of the root, through whose thickness all fluids 

 would have to pass before they reach the alburnum, 

 has at least two offices to perform, either of which 

 might be interfered with by a current fluid setting 

 through it. One of those offices is to convey in a 

 downward direction, or to store up, the matter which 

 has descended to the roots from the branches and 



* [Or sap-wood. Vid. paragr. 49.] 



