SECT. II. ASCENT OF THE SAP. 113 



branches pervading the wood only, but not the 

 pith or bark, the tinge being always deepest at the 

 origin of the leaf and branch. But in the im- 

 mersed portion of the stem, the bark was tinged 

 where the epidermis was wanting ; and in branches 

 of the Fig-tree, the medullary sheath, or sheath sur- 

 rounding the pith, was tinged also. On inspecting 

 the surface of a transverse section of a branch of 

 the Lime-tree that had been made the subject of 

 experiment, the wood was found to be variegated 

 with alternate zones of white and red ; but there 

 was no colouring in the bark or pith. 



In herbaceous plants the case was nearly the 

 same, the streaks being found only in the bundles 

 of woody fibre, though in some examples the upper 

 part of the plant had assumed a reddish tinge, even 

 where no traces of fibre were perceptible. In the 

 leaves the infusion was found to have passed 

 through two different sets of vessels, the one large 

 and longitudinal, the other undulating and twisted ; 

 the former abounding chiefly in the under surface, 

 and the latter in the upper surface. In repeating 

 the experiment of Magnol, M. De la Baisse was 

 completely successful ; and in extending it to a 

 species of Antirrhinum, the infusion was found to 

 have tinged not only the corolla, but also all the 

 other parts of the fructification. 



Bonnet instituted a set of similar experiments Bonnet, 

 on this subject also, in which he used for colouring 

 matter, ink, andx tincture of Madder-root The 



VOL. II. I 



