INTRODUCTION TO PLANT HISTOLOGY 



477 



Cuticle 

 Epidermis 



Hypodermis 

 Cystolith 



Palisade 



y..M Spongy tissue 



Fig. 468. — Ficus elastica. Transverse section of leaf 

 showing cystolith in idioblast cell with supporting 

 cellulose peg. 



Tissue Culture 



As we pointed out at the beginning of this chapter that the plant cell 

 retains its potentiality for regeneration, even when mature, it will easily be 

 grasped that the cultivation of isolated tissues is not possible with plants, 

 as is the case in animals. Small groups of plant cells, if isolated, either die 

 or proceed to develop and differentiate, to regenerate either a complete plant 

 or a complete organ. They do not simply multiply their own kind of cell 

 as do those of animal tissues. This power of regeneration is so great in some 

 plants that a new individual can be raised from even a very small portion of 

 tissue. In the extreme case of Begonia phyUomaniaca it has been achieved 

 from a single hair. Isolated root tips have been subject to much experimenta- 

 tion. They usually regenerate complete root systems, without any shoots 

 or leaves, and if given suitable nutrition, including Vitamins B, and Bg, 

 they may apparently continue indefinitely in their isolated growth. 



