ACTION OF THE ENZYMES. 101 



the same source does not always yield the same impurities. 

 It is therefore entirely probable that the differences which 

 have been assumed to exist in the amylase obtained from dif- 

 ferent sources are only apparent, and depend upon the fact 

 that the impurities accompanying the ferment are different. 

 In this way the same ferment is simply compelled to work 

 under different external conditions, and, as will be shown 

 immediately, the medium in which amylase acts has an im- 

 portant influence upon its action. What has been said here 

 of amylase holds also for the other ferments. 



Amylase brings about two changes when allowed to act 

 upon starch it liquefies the starch and converts it into sugar. 

 The sugar which is formed by amylase when unmixed with 

 other enzymes is the disaccharide, maltose. When amylase is 

 allowed to act upon raw starch granules, the latter are seen 

 to be gradually eroded, and sugar is formed. Upon boiled 

 starch amylase acts far more energetically, the conversion 

 into sugar being accomplished in much shorter time. Accord- 

 ing to KUHNE, the amylase of the saliva does not act upon un- 

 boiled starches at all, while that of the pancreas does. It is 

 entirely probable, however, that this difference is only appar- 

 ent and dependent upon the fact that the concentration of 

 the amylase in the saliva is less than that in the pancreatic 

 juice. The chemical change which starch suffers under the 

 influence of amylase is indicated in the following formula: 



Starch Water Maltose 



This formula shows that starch undergoes a hydration 

 when acted upon by amylase, but it tells us nothing of the 

 mechanism of this change. That maltose is the ultimate 

 product of the catalytic change is almost universally accepted, 

 but opinions differ widely as to the intermediate changes 

 which occur in the starch before the final stage of maltose is 

 reached. All observers are agreed, however, that dextrin is 

 formed in the process of saccharification. Whether the dex- 



