406 Structure o/Ealsamlna Jiortensis. 



From the foregoing experiment of Sir H. Davy, we may 

 conclude that the most impalpable powders can by no means 

 be taken up by the vascular absorbents of plants ; and my own 

 observations upon the two balsams lead to the conclusion, 

 that colouring matter, even in a state of solution, cannot be 

 introduced to the vegetable vessels through the spongioles or 

 porous fibrils of the roots. These consentient evidences tend 

 to throw considerable doubt upon the justness of those deduc- 

 tions that have been drawn from observing traces of colour 

 within cuttings of plants, and young stems or twigs, that had 

 been immersed in coloured infusions of any kind. Cuttings 

 and slips are merely mutilated portions of the subjects from 

 which they have been detached. They retain, it is true, a 

 vestige of the vital principle ; but that lies dormant, and would 

 soon become extinct, were it not excited, and brought into 

 activity, by the stimulus of some appropriate medium, into 

 which, when so placed, other circumstances being propitious, 

 it may protrude roots. 



Though no positive evidence of the exact nature or site of 

 the vessels of conduction has been afforded by my experi- 

 ments, they have tendecj to confirm the ideas I had previously 

 formed. In the first place, the cells, those little vesicles or 

 bladders which constitute the pulp of the stem, were replete 

 with fluid : hence, if not conductors, they are at least depo- 

 sitories of the vegetable juices. Again, the fibrous organs 

 (that is, those bundles of more opaque tubes which pass longi- 

 tudinally along the whole stem, and give out branches to the 

 leaves and leaflets) seemed to be dry ; no vestige of fluid 

 appeared to be in them, as a passing current; if any were dis- 

 cernible, it seemed to have been let or forced in by the 

 violence of the dissection. The fibrous texture, and prodigious 

 elasticity, also, of the organs, demonstrate that they are in 

 every way better adapted to regulate and support the varied 

 motion of the plant, than to act as conductors of its fluids. 

 However, I shall not enlarge further at this time, but content 

 myself with observing, that the fibrous organs of the balsams 

 I examined appeared to me to be placed not far within the 

 epidermis, in small equidistant bundles, and to consist almost 

 entirely of purely spiral fibres, of those more compound 

 organs that have, by some, been styled annular vessels, from 

 the circumstance of their being constructed of a simple mem- 

 branous tube, distended by rings, which rings are separated 

 from one another by a space little exceeding their own breadth. 

 These spaces are discernible by a microscopic power not 

 exceeding one hundred and fifty times. I designate all these 

 appendages to the true sap-vessels fibrous organs \ and I 



