CHAPTER II 



METHODS OF ESTIMATING CARBOHYDRATES IN PLANT 

 EXTRACTS 



IN forming an opinion of the value attaching to the results 

 of carbohydrate analyses, due regard must be paid to the 

 accuracy of the methods employed in obtaining them. It 

 is with the object of doing this, as well as because the 

 methods themselves are frequently of biological interest, 

 that the present chapter has been inserted.* 



PREPARATION OF MATERIAL AND ANALYSIS ACCORDING TO 

 BROWN AND MORRIS. 



The estimations may be based upon the fresh or dry 

 weight of tissue taken. In either case it is necessary to 

 extract with a solvent. The particular method of extrac- 

 tion employed is of great importance, since the carbo- 

 hydrates are readily attacked both by the naturally oc- 

 curring tissue enzymes and by acids. 



Confining the problem to the analyses of mixtures of 

 starch, maltose, sucrose, glucose, and fructose, it is obvious 

 that the first-mentioned can readily be separated, so that 

 extracts contain only the sugars. 



Brown and Morris (1893) tried to make use of juice 

 expressed from the leaves, but, finding that there was a 

 difficulty in calculating the sugars back to the dry weight, 



* For detailed information a textbook such as Browne's " Handbook 

 of Sugar Analysis" should be consulted^ or the original memoirs should 

 be read. 



