CHEMICAL PHENOMENA IN LIFE 



by which process the expansion of the cell wall 

 becomes permanent. 



The most striking feature of cell life is the 

 fact that an enormous number of chemical re- 

 actions take place within the narrowest space. 

 Most plant cells do not exceed o-i to 0-5 

 millimetres in diameter. Their greatest volume 

 therefore can only be an eighth of a cubic milli- 

 metre. Nevertheless, in this minute space we 

 notice in every stage of cell life a considerable 

 number of chemical reactions which are carried on 

 contemporaneously, without one disturbing the 

 other in the slightest degree. How can we explain 

 this striking phenomenon ? In the first place we 

 must state that polioplasm is highly specialised 

 in its different parts. Besides the nucleus, which 

 certainly is the seat of most important vital 

 activities, we find many organs which are to be 

 recognised with the aid of the microscope as 

 distinct protoplasmatic organs, and we already 

 know the functions of many of them. Most plant 

 cells contain clearly differentiated small bodies of 

 different shape which are employed in the service 

 of the assimilation of sugar and carbohydrates. 

 In common plants they are green in colour, and 

 possess the remarkable power of absorbing carbon 

 dioxide, if bright light is admitted, and of forming 

 sugar from the carbon dioxide and water. These 

 are the chlorophyll bodies or Chloroplasts. Very 

 little is as yet known about their detailed structure. 

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