vw VC.KOI i Y 



FERMENTATION 243 



The zymase attacks only those sugars which present 

 a specific stereo-configuration. The position of their 

 atoms in space must fit the position of the atoms of 

 the ferment (the lock and the key). Thus, only the 

 dextro-rotatory forms of the aldehyde sugars (d-glu- 

 eose, d-mannose, d-galactose) are attacked ; the sugars 

 that rotate the plane of polarized light to the left 

 are not attacked. It is probable that the zymase 

 of different species of yeast presents characteristic dif- 

 ferences. It is known that the products formed in the 

 fermentation of sugar by different species of yeasts are 

 to a large degree characteristic. Often these products 

 are injurious. Upon this specific action of ferments 

 rests the work of Hansen, 1 who taught the brewers to 

 make pure cultures of the most favorable species of 

 yeast, and thereby raised the brewing industry to the 

 level of an applied science. 



ACTIVATING FERMENTS 



Enterokinase. In 1899, Chepowalnikow, 2 in 

 Pawlow's laboratory, found that pancreatic juice 

 obtained by Pawlow's 3 method contained very 



1 HANSEN : Untersuchungen an der Praxis der Gahrungs- 

 Industrie, 1895. 



2 CHEPOWALNIKOW : Thesis (Russian), St. Petersburg, 1899, 

 Paris, 1901. 



8 In Pawlow's method the intestine is resected and the 

 portion of the intestinal wall containing the opening of the 

 pancreatic duct is stitched to the edges of the abdominal wound, 

 where it soon unites ; the pancreatic duct then discharges upon 

 the surface of the abdomen, where the juice may be caught by 

 applying a suitable vessel. 



