ACTION OF THE ENZYMES. 143 



looks as though this further synthesis of albuminous sub- 

 stances has been accomplished and by means which we can 

 well imagine active in the living organism. 



Of first interest in this direction is the work of OKOUNEFF, 

 who, in 1895, showed that through the action of trypsin on a 

 concentrated solution of proteoses the latter suffers a physi- 

 cal change in that flakes appear in it, or in that the whole 

 assumes a jelly-like consistency. This change in consist- 

 ency (increase in viscosity) has been shown to occur not only 

 under the influence of alkali-proteinase (trypsin), but also 

 acid-proteinase (pepsin) and ampho-proteinase (papain). 

 It is a change, therefore, which is brought about in a solu- 

 tion of proteoses by any of the ordinary so-called proteo- 

 lytic ferments. 



What is the character of this change in viscosity? This 

 question has been investigated by a number of observers 

 from both a chemical and a physical standpoint, and the 

 results obtained by each indicate very strongly that the proc- 

 ess of the formation of "plastein," as the above is called, 

 represents a reversion, under the influence of the proteolytic 

 ferments, of proteoses into more complicated proteins. From 

 a chemical standpoint, proof in this direction has been brought 

 especially by SAWJALOW, 1 who has succeeded in obtaining 

 from a proteose solution upon which a proteolytic ferment 

 had been acting for some time, and which originally had been 

 free from this reaction, a coagulum on boiling after the addi- 

 tion of acetic acid. This is a reaction which, it is well known, 

 is considered characteristic of the albumins. 



The change which occurs when "plastein" is formed has 

 been investigated from a physical standpoint by HERZOG, 2 

 and to him belongs the credit of recognizing in it the reversible 

 activity of a proteolytic ferment. 



1 SAWJALOW: PHiiger's Archiv, 1901, LXXXV, p. 171; Centralblatt 

 fur Physiologic, 1903, XVI, p. 625. 



2 HERZOG: Zeitschrift fur physiologische Chemie, 1903, XXXIX, p. 

 305. 



