PAPAIN-PROTEOLYSIS. 169 



mose. Moreover, it is seen that as the digestion is continued 

 the proportion of albumoses decreases, peptones being corre- 

 spondingly increased. To be sure, the figures representing 

 the proportions of peptone formed are obtained by difference, 

 but we see no reason why the methods pursued are not capable 

 of yielding results substantially correct. Moreover, on testing 

 the three ammonium sulphate-saturated filtrates containing 

 the peptone with the biuret test, the intensity of the reactions 

 obtained corresponded exactly with the above data. In this 

 connection it should be mentioned that even under most 

 favorable conditions the formation of amido-acids or other 

 crystalline decomposition products by papain is very slight. 



A second series of experiments similar to the above next 

 demand attention because they help make clear possibly why 

 some observers have failed to find evidence of the formation of 

 peptone by papain. Four distinct mixtures were prepared, 

 each containing 150 c. c. of 0.25 per cent sodium carbonate 

 saturated with chloroform, 50 grams of moist coagulated egg- 

 albumin, and 0.5 gram of papain. The fourth mixture, however, 

 differed from the other three in that the papain was boiled 

 with a portion of the fluid prior to mixing it with the albumin. 

 It thus served as a control to check any possible errors that 

 might arise from the action of the alkali alone on the proteid, 

 or from soluble matter contained in the papain. Of greater 

 importance, however, is the fact that the proportion of papain 

 employed in this series of experiments was considerably less 

 than in the previous series : i. e., 0.5 gram instead of 0.75 gram 

 for every 50 grams of proteid. Furthermore, the papain was 

 a different sample, obtained from a different source, and had 

 been tested solely as to its ability to dissolve proteid matter. 



The several mixtures were kept at 38-40 C. for varying 

 periods of time, one being removed at the end of 25 hours, the 

 second at the end of 48 hours, while the third and fourth were 

 continued for 72 hours. The mixtures were then analyzed as 

 in the preceding case, with the following results expressed in 

 grams: 



