Elementary Botany 



CHAPTER III. 



CELL STRUCTURE. 



The substance of the Bean seed is not homogeneous. The 

 whole of the various organs of plants are made up of a large 

 number of component parts— cells, so minute as a rule as to 

 be invisible separately to the naked eye. If a little brewer's 

 Yeast be examined under a hand magnifying glass, it is seen 

 to present a granular appearance. If it be more highly magni- 

 fied, it is found to consist of a large number of minute rounded 

 particles (fig. 4) ; these are separate cells. We recognise in 

 them the outer pellicle or cell wall and the cell contents. 



Fig. 4.— Beer Yeast {Saccha- 

 roinyees \Toruld\ Cere- 

 I'isiee). 



Fk;. S-— a cell from the root of the Lizaril 

 Orchis _(t??r/i/j kircina) ; a, the cell-wall, 

 consisting of cellulose ; b^ the protoplasm, 

 contracted by alcohol ; c^ the nucleus 

 with a nucleolus. 



The cell wall may be absent during a portion of the cell's 

 existence ; it is simply inert, not-living matter ; but in the 

 Vegetable Kingdom it is always sooner or later produced. The 

 principal substance contained in it is cellulose, a compound of 

 carbon, hydrogen, and oxygen, having the chemical composi- 

 tion (CeH.oO,)^ 



