ACTION OF THE ENZYMES. 149 



itself par excellence upon the peptones. As the proteoses 

 constitute, with the exception already given, the chemically 

 most complex substances upon which COHNHEIM'S ferment 

 acts, it has been called protease. 



Through the investigations of a number of authors, more 

 especially VERNON, 1 we have become acquainted with the 

 presence of protease in other tissues besides the small intes- 

 tine. It is very probable that this fact will necessitate a 

 revision in our knowledge of the ultimate digestion-products 

 of alkali-proteinase, for the two ferments are frequently 

 present in the same tissues, and no doubt some of the sub- 

 seances which are to-day believed to have been produced 

 through the activity of the alkali-proteinase are really pro- 

 duced through the protease which is present simultaneously 

 and which has not been considered in the analyses at present 

 at hand. Of interest also in this connection is the fact that 

 the "BENCE-JONES protein," which appears in the urine in 

 certain pathological states, is not acted upon by protease. 

 This seems to indicate that it does not belong to the pro- 

 teoses (albumoses) , under which heading it is usually classi- 

 fied. 



Protease, like other ferments, is markedly affected by the 

 character of the medium in which it is active. It acts best 

 in an alkaline medium, although it is still able to bring about 

 its characteristic effects in one having an acid reaction. 



ii. Lipase. Under the term lipase (steapsin) or the 

 lipases we understand those ferments that have the power 

 of acting upon neutral fats of various kinds and splitting 

 these into their constituent fatty acids and alcohols. The 

 earlier investigators believed that the formation of an emul- 

 sion from the fat represented one of the characteristic prop- 

 erties of lipase. This is not true, however. The distinguish- 

 ing property of lipase resides in its power of bringing about 

 not a physical but a chemical change in the fat. While we 



1 VERNON: Journal of Physiology, 1904, XXXII, p. 33. 



