LECT. Hi.] VASCULAR TEXTURK. 87 



Flowering Rush, says that author, "I have seen 

 long portions of vessels present, at intervals, the 

 appearance of an unrolled trachea, a transversely 

 cleft vessel, and a porous vessel." 



Besides these vessels, Hedwig imagined there 

 existed lymphatic, or absorbing vessels, opening 

 upon the cuticle, and forming a circle round the 

 exhaling pores : a doctrine, which has been adopted 

 by Willdenow and others ; but which Mirbel justly 

 combats, alleging " that the sides of the cells 

 which terminate in the cuticle, and the fragments 

 of which remain fixed to that pellicle when it is 

 detached, have been mistaken for lymphatic ves- 

 sels by Hedwig *." 



Mirbel mentions another set of vessels, which 

 he denominates little tubes ; but they may rather 

 be regarded as tubular cells, than vessels, being 

 closed at the extremities. They resemble, very 

 much, stretched cellular substance, except that 

 the membrane composing them is less transparent, 

 and of a greater consistence. The solidity of 

 plants depends very much on the quantity and 

 density of these cells, which are filled with thick 

 and coloured, or thin and colourless juices, ac- 

 cording to the nature of the plants in which they 

 exist. 



Such is the vascular system of vegetables, 



* Elem. de Phys. veget. 1* Partic, p. 40. 



c4 



