124 PHYSIOLOGICAL CHEMISTRY. 



secured by extracting with 20 per cent alcohol and precipitat- 

 ing the solution so obtained by absolute alcohol. This precipi- 

 tate in turn may be redissolved in water and precipitated again 

 with strong alcohol or with ammonium sulphate, to secure a 

 purer and more active product. 



Besides the well-known ferments in malt, in the saliva and 

 in the pancreatic secretion the following may be mentioned 

 here. By many authors the active substance in the liver 

 which converts glycogen into glucose is supposed to be a form 

 of diastase. Others hold the conversion of sugar into glyco- 

 gen and the subsequent and gradual formation of sugar from 

 glycogen to be specific vital functions performed by the liver 

 cells. The name cellulase or cytase is given to a ferment body 

 which is found in many vegetable substances and which has 

 the power of converting cellulose into sugar. Inulase is the en- 

 zyme which acts on the peculiar starch known as inulin found 

 in many vegetable substances, converting it into fructose. Inu- 

 lase does not appear to act on ordinary starch and on the other 

 hand, malt diastase is not able to convert inulin into sugar. 

 Pectinase is another little known vegetable enzyme which con- 

 verts the so-called pectin jelly substances into a reducing sugar. 

 The original pectose in the seed or fruit is first changed into 

 pectin by a kind of coagulating enzyme called pectase. The 

 true behavior of these bodies is not yet fully known. 



Maltase or Glucase. The sugar formed by amylase from 

 starch is known as maltose. This is a primary product and 

 may readily be further converted into glucose by another en- 

 zyme occurring in malt and properly known as maltase. The 

 nomenclature of these enzymes is unfortunately somewhat 

 confused. An effort has been made to name them systemat- 

 ically, using in each case the name of the carbohydrate or other 

 body on which the enzyme acts, as the first part of the descrip- 

 tive term, to be followed by the suffix ase. Thus amylase re- 

 fers to the enzyme acting on amylose or starch and maltase 

 to the enzyme which acts on maltose or malt sugar. But 

 many authors do not follow this system consistently; hence 



