112 HISTOLOGICAL BOTANY. 



1. KINDS OF TISSUE-SYSTEMS. 



If the petiole of the Obako be broken across, tough 

 bundles will be observed, and a thin transparent skin may- 

 be easily stripped off from its surface. These bundles are 

 chiefly composed of vessels and prosenchyma, and are called 

 Fibro-vascular Bundles. They traverse the plant-body 

 and form the Fibro-vascular System. The thin skin cover- 

 ing the plant-body is called the Epidermal System. That 

 group of tissues which is situated within the latter and 

 encloses the fibro-vascular bandies, is termed the Funda- 

 mental System. 



Kinds op tissue-systems- 



Fundamental System. 

 Fibro-vascular System. 

 Epidermal System. 



The Fundamental System. — This system consists 

 principally of parenchyma from which all the other tissues 

 are derived. 



The Fibro-vascular System. — This system consists 

 of prosenchyma, vessels, and a few parenchymatous cells, 

 arranged in bundles which run longitudinally through the 

 plant-body. 



Parts of the Fibro-vascular Bundle. — Each fibro- 

 vascular bundle is composed of two portions, an inner and 

 an outer. The inner portion is hard when well developed 

 and consists of woody vessels, woody prosenchyma, and 

 hard parenchyma ; and the outer is comparatively soft and 

 eonsists of bast vessels, bast prosenchyma, and soft paren- 

 chyma. 



The former portion is called the Xylen or Wood, and the 

 latter the Phloem or Bast 



- ■ ( Xylem. 



Parts of the fibro-vascular bundle | p £ 



