5Cy VEGETABLE ORGANOGRAPHY, 



CHAPTER IV. 



OF THE FIBRES AND WOODY LAYERS. 



When a stem of a vascular plant is cut transversely, we 

 observe a certain number of points more compact than 

 the rest of the tissue ; if it be cleft lengthways, we do 

 not fail to remark that these points are the ends of so 

 many longitudinal bundles, which separate more easily 

 from the rest of the tissue without being broken ; these 

 bundles bear the name of Fibres, (^6r<^.^ 



If we examine them with the microscope we easily 

 perceive that a fibre is not a simple organ, but that it is 

 composed of bundles of vessels intermixed and sur- 

 rounded by elongated cellular tissue. In common prac- 

 tice, when it is wished to procure the fibres of plants 

 isolated, the plants are placed in water to macerate, and 

 after some time the fibres seem to separate spontaneously ; 

 this is what constitutes the maceration of Hemp, Flax, 

 Agave, Phormium, &c. But this operation in reaHty 

 disorganizes the vegetable tissue ; in fact, it exposes to 

 the action of the water a tissue composed of parts which 

 are capable of being altered in different degrees by that 

 liquid : the water first affects the softer and less compact 

 parts — viz. the regular cellular tissue ; and by it separates 



