114 BACTERIOLOGICAL AND ENZYME CHEMISTRY 



hydrazine is added, together with 0'2 gram of sodium acetate ; 

 the whole is warmed until solution takes place and then 

 heated half an hour on a boiling water-bath. 



Glucosazone formed in this way from glucose is almost 

 insoluble in water, and has a melting-point 225° C. The 

 osazone of maltose is soluble in 75 parts of water at 100° C, 

 and its melting-point is 205° C. Maltose is further distin- 

 guished from glucose by its specific rotatory power, which 

 is 140 degrees compared with 52-5. The cupric oxide reducing 

 power is two-thirds that of glucose. 



The methods of investigation which have just been 

 described render it possible quantitatively to foUow the 

 changes taking place in the course of the action of amylase 

 upon starch. A large number of investigators have pub- 

 lished researches on this subject, the general result of which 

 has been to lead to the conclusion that the starch molecule 

 breaks down by a series of hydrations and subsequent decom- 

 positions, maltose being formed at each splitting, together 

 with a dextrin of less molecular weight. Certain of these 

 dextrins, as the quahtative examination of the reaction 

 showed, give characteristic colour reactions with iodine, the 

 red colour, e.g., being due to a dextrin termed erythro-dextrin. ' 



Brown and Morris noted that when 80 per cent, of maltose 

 and 20 per cent, of dextrin had been formed, the last 20 per 

 cent. hydroUsed with difficulty, and they assumed the forma- 

 tion of a body intermediate between maltose and dextrin 

 which they termed malto-dextrin. Their theory to account 

 for this assumes that the starch molecule breaks up into a 

 stable dextrin and so-called amylin groups which are capable 

 of gradual hydrolysis to maltose ; we have thus the following 

 equations : — 



5[(CiAoOio)2o] = (CiAoOio)2o + 4 [{0,^2.0 J^] 



Starch, Stable dextrin Amylin groups 



