246 ORGANIC AGRICULTURAL CHEMISTRY 



EXPERIMENT STUDY XXXn 



Action of Diastase on Starch 



(a) Extract 50 grams of finely ground malt (germinated barley) with 

 warm (25°-30° C.) water. Filter and test filtrate for reducing sugars 

 (maltose or glucose). Ferment this filtrate with yeast until all fer- 

 mentable sugars (maltose and glucose) have been converted into 

 alcohol. Filter again if necessary and retest for reducing sugars. 

 No test should be obtained. Make a little starch paste, add the 

 filtrate to this paste, and keep at 35° C. After a day test for starch 

 and reducing sugar. 



(b) Prepared diastase may be used instead of the extract of malt if 

 desired. 



Building MateriaL — We have discussed thus far two of the 

 functions fulfilled by the photosynthesized carbohydrates, viz. 

 (i) in the form of soluble sugars, probably always as glucose, 

 to furnish the plant cells with food material for oxidation and 

 the liberation of the energy of the living processes. (2) To be 

 converted into starch as a temporary reserve material in leaves 

 or as a reserve food for the germ of the plant's offspring in the 

 seed, tuber, root, etc. 



One more function fulfilled by photosynthesized carbohy- 

 drates is to be mentioned in more detail, viz. the conversion of 

 it into material out of which the body substance of the plant 

 is built. This building of body material is the second distinct 

 function of food. 



In our study of animal food and nutrition we defined food, 

 more especially the organic food, as any substance which 

 taken into the body is used to build body material or to yield 

 energy. Nutrition embraces all of the processes by which these 

 functions are performed. The changes involved constitute 

 metabolism, which is either constructive (anabolism) or destruc- 

 tive (katabolism). The result of anabolism is the building of 

 body material which may be either temporary or more or less 

 permanent. The result of katabolism is the yielding of energy. 

 The metabolic changes which we have been considering in 



