CHAPTER II 

 THE PLANT CELL 



CERTAIN aspects of the physiology of complex organisms 

 may be convincingly presented and perhaps adequately 

 understood without necessarily assuming any knowledge 

 of the minute structure of such organisms. In the same 

 way the demonstration of important chemical facts and 

 reactions may be measurably feasible and instructive 

 for those with little or no conception of the significance of 

 atoms and molecules. Nevertheless, in the same way that 

 a knowledge of the atom is indispensable in understanding 

 chemical theory, just so the minute structure and the re- 

 lations of cells is fundamental in order to gain a compre- 

 hensive view of the activities of a multicellular organism. 



A century ago it became apparent to a few physiologists 

 that some .fundamental physiological problems could find 

 more nearly complete solution only through experimental 

 studies upon the cell. In the time which has since elapsed 

 the relative importance of cell physiology has been more 

 and more appreciated. Advances in this field, however, 

 are necessarily associated with advances in morphology, 

 chemistry, and physics. The development of cell mor- 

 phology has been dependent largely upon the improvement 

 of the microscope, and of current methods of technique, 

 both of which have now reached a high state of per- 

 fection. Physical and chemical theory and method have 



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