KINDS OF TISSUE-SYSTEMS. 113 



Kinds of Eibro-vasctjlar Bundles. — Some fibro-vas- 

 cular bundles possess a layer of generating tissue called the 

 Cambium between the xylem and the phloem, as in the 

 stems of the Sakura and Akamatsu ; while others want the 

 cambium, as in the Oniyuri and Nokishinobu. Those of 

 the former kind increase the bulk of the xylem and of the 

 phloem by the growth of cambial cells, and are said to be 

 Open ; and those of the latter are incapable of any further 

 growth, and are said to be Closed. 



iOpen Fibro-vascular 

 Bundles. 

 Closed Fibro-vascular 

 Bundles. 



The Epidermal System. — This system consists of more 

 or less modified parenchyma. 



Parts of the Epider- fig. 124. 



mal System. — When well 

 developed, this system is 

 composed of a membrane, 

 consisting of one or more 

 layers of parenchymatous 

 cells, perforated by numer- 

 ous openings, and pro- Fi G . 124.— Epidermis of the leaf of 

 Vided With various pro- the Kabura, showing stomata. 



tuberances. The membrane is called the Epidermis ; the 

 openings through the latter, Stomata (Eig. 124) ; and 

 the protuberances on the surface, Hairs. 



The epidermis consists of those cells which are in close 

 juxtaposition without any intercellular spaces except at the 

 points where it is perforated by the stomata. (See Eig. 118.) 

 The upper cell-walls of the epidermis are usually cuti- 

 cularized and are rendered impermeable to water ; but in 

 submersed or very young parts the epidermal cells are not 



