SOME RECENT RESEARCHES IN 

 PLANT PHYSIOLOGY 



CHAPTER I 



THE CARBOHYDRATES OF THE ANGIOSPERM LEAF IN 

 RELATION TO PHOTOSYNTHESIS 



THE presence of sugars and of starch in green leaves exposed 

 to light has been established for many years, yet the relation- 

 ship of the various carbohydrates to one another is as yet 

 undecided. Sachs pointed out that starch is the first 

 visible product of assimilation, though he did not deny that 

 the immediate source of the starch granules was of the 

 nature of a sugar dissolved in the chloroplast. The changes 

 preceding starch formation, as well as those concerned in 

 its dissolution, were the subject of the classical researches 

 of Brown and Morris (1893). These authors give a critical 

 summary of previous work, and as this is both readily 

 accessible in the original, and has been incorporated in text- 

 books, it will not be considered here at any length. 



As the work of Brown and Morris laid the foundations of 

 the accurate analysis of carbohydrate mixtures occurring in 

 plant tissues, and has also been the starting-point for 

 several subsequent researches, it is advisable to discuss its 

 results in detail even though they are well known. The 

 analytical methods employed will be treated of in a separate 

 chapter for the sake of clearness. 



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