juiy 3,1916 Effect of Autolysis upon Muscle Creatin 541 



cent of creatinin as compared with the fresh material. Samples incubated 

 for periods ranging from 64 to 100 days show slight and irregular decreases 

 in free creatinin as compared with the sample incubated 42 days. 



The creatin content of the samples, which is calculated by subtracting 

 the percentage of free creatinin from that of total creatinin, shows 

 decreases which correspond to the increases in free creatinin. 



The relation between the free creatinin and total creatinin is of special 

 interest. The fresh material contains 2.08 per cent of the total creatinin 

 in the form of free creatinin, while in case of the sample incubated for 

 7 days the percentage has increased to 21.42. The increases in suc- 

 ceeding periods are less rapid, until a maximum increase is reached in 

 case of the sample incubated 42 days, which contains 46.40 per cent of 

 the total creatinin in the form of free creatinin. However, practically 

 the maximum increase is reached in case of the sample incubated 28 days 

 in which 46.38 per cent of the total creatinin is in the form of free 

 creatinin. 



These results show that under the conditions of the experiment an 

 equilibrium is established between the creatinin and creatin. These find- 

 ings confirm in a remarkable degree results obtained by Myers and Fine 

 (5) in their work with pure solutions of creatin and of creatinin. They 

 incubated solutions of the individual bases for a total period of 337 

 days, and determined free and total creatinin in each of the solutions 

 at intervals. In case of the solution of creatin, it was found that there 

 was a gradual change of creatin into creatinin until at the end of the 

 period an equilibrium had been established with 44.45 per cent of the 

 total creatinin in the form of free creatinin. In case of the solution of 

 creatinin the change was in the other direction, there being a decrease 

 in creatinin and an increase in creatin, until at the end of 337 days an 

 equilibrium had been established with the relative proportions of creatin 

 and creatinin identical with those noted above. 



It is not to be inferred from these findings that the changes which 

 took place in the creatin and creatinin content of muscular tissue during 

 autolysis are entirely natural changes of one base into the other. In 

 case of the autolytic experiments with muscle, practically the maximum 

 change of creatin into creatinin had taken place at the end of 28 days, 

 and nearly half of the total change had taken place in 7 days. 



In Myers and Fine's experiments (5) with a solution of pure creatin 

 only 9 per cent of the total creatinin was present in the form of free 

 creatinin at the end of 13 days, and after 53 days only 29 per cent. In 

 our autolytic experiments with muscle, on the other hand, 25.41 per 

 cent of the total creatinin was in the form of free creatinin at the end of 

 7 days, and 46.31 per cent at the end of 28 days. 



It is very evident that the rate of change of creatin into creatinin 

 during the autolysis of beef muscle was greatly accelerated by some agent. 

 The acids in the meat may have facilitated the change in some degree; 



