PREFACE 



IT has given me great pleasure to accept the 

 suggestion of the Editor of Harper's Library 

 of Living Thought, that I should treat in a volume 

 of this series some phases in the life processes of 

 plants. 



There is scarcely any other question in the 

 biology of plants of greater interest than that 

 of the general chemistry of the cell, viz. of the 

 living protoplasm, which has been so successfully 

 worked at by the biochemists of our time. Not 

 only very important results, but also most sug- 

 gestive hypotheses, render this chapter of plant 

 Physiology more attractive than any other. The 

 molecular structure of living protoplasm, as well 

 as organic synthesis in cells and the hitherto 

 inexplicable phenomena of endosmosis in the cell, 

 have been rapidly placed in the foreground of 

 modern scientific problems and now range among 

 the great questions of biology to solve which is a 

 well-grounded hope. 



So I could not resist the temptation to give a 

 short review of this territory of Biology which is so 

 full of suggestions and attractions. I was, however, 



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