258 



Anatomy of the Vine. 



You may observe that no alburnum is represented in Jig. 46., 

 nor any mentioned in the description of vessels A to be attached 

 to the liber, for none can be produced until the leaves are 

 tolerably well expanded. 



Again, cut through the twelfth ^^^T '^mr- s 



or still lower collet, when the ves- |§|j ff~ f 



sels will be found more matured 

 and more visible ; the liber, when 

 the sulphate of iron is placed 

 upon it, will now show a much 

 darker precipitate, part of the al- 

 burnum will be discovered, and the 

 apertures of its ascending sap-ves- 

 sels will be distinctly seen : by re- 

 ferring to Jig.- 47. the difference be- 

 tween this and the former figure 

 (46.), may be easily distinguished, 

 and also by the following descriptioil 

 of vessels, B, of Jig. 47. 



[B.] _ 



a, Medulla 



b, Spiral vessels 



c, Concentric layer 



d, Ascending sap-vessels - ; ' ■ 



e, Liber 



f, Vascular texture 



g, Cellular vessels and cuticle 



The extended leaves are now capable of exerting their full 

 powers, not only on the fluid furnished them by the spiral ves- 

 sels, but also upon the sap which they derive from the roots 

 by the ascending sap-vessels, which latter undergoes certain 

 chemical changes, and perhaps the other also, by imbibing the 

 atmospheric air, which oxygenates it, by the influence of the 

 rays of the sun ; and these fluids afterwards descend by the 

 liber and the vascular vessels ; and a gradual increase of albur- 

 num is produced, but principally by the vessels of the liber. 



Repeat a similar experiment on some of the lower collets 

 of the shoot, when the vessels will be still more apparent, and 

 a greater increase of alburnum will be seen. I consider these 

 simple experiments to be very satisfactory : they are not only 

 conclusive, as to the gradual growth of the alburnum in the 

 summer shoot of the vine, but that no part of it is converted 

 liber, as the liber is still in its original state ; these experiments 

 are the more pleasing, as they require so short a time to 

 establish two such evident facts. 



The cellular texture I shall now endeavour to describe : its 

 vessels are of the utmost importance to every plant ; in short, 



The further advanced state of 

 the vessels of a collet, of a 

 summer's shoot of a vine. 



