CLASSIFICATION. 117 



1. The Proteolytic Ferments (Proteases). These comprise the com- 

 mon digestive ferments of the stomach and pancreas, viz., pepsin 

 and trypsin ; the autolytic ferments which are responsible for the 

 aseptic autodigestion of the various organs after death, and analo- 



fms ferments which are widely distributed in the vegetable world, 

 hey all digest the various albumins with the formation of albu- 

 moses and those end-products of hydrolysis which are collectively 

 spoken of as peptones. While their activity is generally speaking 

 specific (see preceding page), it is noteworthy that some proteolytic 

 ferments will also hydrolyze the nucleinic acids (Araki) ; trypsin is 

 a notable exception to this latter rule. 



Closely related to the proteolytic ferments is the erepsin which O. 

 Cohnheim demonstrated in the intestinal mucosa; its specific activity 

 is directed to the hydrolysis of albumoses, while albumins are not 

 affected. 



Rennin and thrombin are two coagulating ferments which are 

 sometimes classified under the proteolytic ferments. The first co- 

 agulates milk, the latter the blood. 



2. The Amylolytic Ferments (Amylases, Diastases). These include 

 the ptyalin of the saliva, the diastatic ferment of the pancreatic 

 juice, certain endocellular diastases, the so-called vegetable diastase 

 and related ferments, which may be obtained from bacteria. Some 

 of these only render starch soluble, while others also cause its hy- 

 drolysis to disaccharides. 



3. The Inverting Ferments (Invertases). These are apparently 

 related to the amylolytic ferments, and are to a certain extent iden- 

 tical with them. They invert the disaccharides to monosaccharides, 

 and according to their specific effect upon cane-sugar, maltose, and 

 lactose, they are termed invertins (invertases), maltases, and lac- 

 tases, respectively. Such ferments are found in the saliva, the pan- 

 creatic juice, the enteric juice, in many of the higher plants, and also 

 in numerous organized ferments. 



4. The Lipolytic Ferments (Lipases). Lipases are extensively dis- 

 tributed in the animal body. They occur in the gastric and the 

 pancreatic juice, and are possibly represented in all tissues. In the 

 vegetable world also they are common ; lipases have been found in 

 the seeds of ricinus, of the poppy, of cannabis sativa, in linseed, 

 corn, etc. They cause the hydrolysis of fats to fatty acids and 

 glycerin. 



5. The ureases, viz., ferments which decompose urea with the for- 

 mation of ammonia. Such ferments are present in many bacteria, 

 such as the Micrococcus urese, Bacterium urese, Bacillus fluorescens, 

 etc. A ferment of this order has also been demonstrated in the liver. 



6. Ferments which transform amido-acids into amides occur in the 

 liver and the kidneys, and have also been demonstrated in plants. 



7. The Histozyme of Schmiedeberg. This is found in the kidneys 

 and is characterized by its ability to decompose hippuric acid with 

 the formation of benzoic acid and glycocoll. 



