92 TISSUE FERMENTS 



reached a definite conclusion many fundamental problems 

 of physiology and of pathology will be regarded very 

 differently than is now possible. 



Detection of Proteolytic Tissue Ferments, by Employing 

 Glycylty rosin, Silk-peptone and Glycyltryptophane. Men- 

 tion may first be made of some part at least of the 

 progress in technique contributed by Abderhalden in this 

 field. A useful method of determining peptolytic tissue fer- 

 ments is based upon their action on a solution of some poly- 

 peptid, which, like glycyltyrosin or a given silk-peptone, 

 contains a relatively insoluble aminoacid. The ferment 

 solution to be tested or a section of an organ is put in a 25 

 per cent, solution of silk-peptone and placed in the incubator 

 after toluol has been added ; after a few hours presence of 

 the ferment manifests itself by the separation of tyrosin. 

 The tyrosin is to be found limited to the cortical surface of 

 sections of renal tissue, for example, the medulla remaining 

 free; in fatty kidneys the tyrosin separation is distinctly 

 decreased. It is equally simple to determine the presence of 

 peptolytic ferments in sections of vegetable material. An- 

 other process which is also available for microchemical work 

 is based upon the fact that a polypeptid containing trypto- 

 phane, as glycyltryptophane, when treated with bromine 

 water will yield a violet color, not at once, but after the 

 separation of the tryptophane. 



Optical Method. The "optical method " introduced by 

 Emil Fischer and Abderhalden has yielded excellent results 

 in this freld ; the author has previously referred to this (Vol. 

 I of this series, p. 555, Chemistry of the Tissues, and in the 

 present volume, Chapter II). This method demands the use 

 of a suitably sensitive polarization apparatus with which to 

 follow and accurately determine each step of the course of 

 cleavage of optically-active polypeptids in which the indi- 

 vidual "building stones" are loosened from their structural 

 positions in the complexly constructed polypeptid. An illus- 



