RECENT WORK ON PROTEIN-HYDROLYSIS 439 



peptone. Martin found that he obtained it from fibrin, but not 

 from globulin, and only traces from the proteases of the plant. 

 Halliburton found peptone when he used animal proteids, but 

 not when he employed vegetable. Other writers found some- 

 times traces of peptone and sometimes none. 



Other differences of opinion may be found on the question of 

 the most suitable reaction for the process of papain digestion. 

 Wurtz and others, particularly Martin, found a neutral medium 

 like that of fresh papai'n-juice was most advantageous, Davis 

 says that a trace of acidity or of alkalinity causes acceleration, 

 while Emmerling finds the best medium for its digestion of 

 fibrin is a slightly alkaline one. 



To test the matter more exhaustively Vines used three 

 distinct samples of commercial papain, obtained from Messrs. 

 Christy, Finckler, and Merck respectively, worked with digesting 

 fluids of different reactions, and used various antiseptics, care- 

 fully controlling all the experiments. As he expected, he found 

 a good deal of difference in the preparations on all the points 

 under investigation. 



The experiments not only threw a certain amount of light on 

 the conflicting results of the earlier observers, to a certain 

 extent explaining them, but they were found to have a very 

 direct bearing on the question already stated as to the presence 

 of one enzyme or two in the papaw. Christy's papain readily 

 digested or dissolved fibrin in the presence of fluoride of 

 sodium, but it could not split up peptone. Finckler's papain 

 did the same in the presence of hydrocyanic acid ; Merck's 

 preparation resembled Finckler's when used in a weak solution. 

 Christy's papain when digested with peptone in presence of 

 toluol in an acid medium gave a strong tryptophane reaction, 

 but had hardly any action on fibrin. 



Altogether the experiments lent support to the theory that 

 commercial papain contains a pepsin and an erepsin. 



Vines found in other experiments that nepenthin, contained 

 in the liquid in the pitcher of Nepenthes, converts fibrin into 

 peptone with great rapidity, but only very slowly breaks up 

 peptone when set at the outset to work upon it. The course 

 of the experiments show, that the fibrin digestion is so much 

 more active than peptolysis as to suggest the presence of 

 pepsin and erepsin, the former in much the larger quantity. 



In a very considerable number of cases in which he examined 



