i6 



Scientific Proceedings (55). 



to detect the presence of creatinine. We believe we have demon- 

 strated that creatinine does exist in very small quantity in muscle 

 (rabbit), equivalent to about one per cent, of the creatine. The 

 quantity appears to average 6 or 7 mgm. per 100 grams of moist 

 muscle, although variations of 3 to 10 mgm. have been encountered. 

 An observation which is much more significant, however, is that, 

 when the muscle is allowed to autolyze at body temperature 

 under antiseptic conditions, the creatinine content increases at a 

 very uniform rate at the expense of the muscle creatine. One 

 experiment may be cited. The muscle of Rabbit No. 77 had an 

 initial creatinine content of 6 mgm. per 100 grams; at the end 

 of 2 days this had increased to 20.2 mgm., in 4 days to 36.6 mgm., 

 in 6 days to 50.6 mgm., in 8 days to 62.5 mgm., and in 10 days to 

 74.5 mgm., an average uniform daily increment of 7 mgm. per day. 

 This fact, when considered in connection with the uniform content 

 of muscle creatine previously observed by us, 1 is, we believe, the 

 fundamental factor in bringing about the constant daily excretion 

 of creatinine originally observed by Folin. When pure creatine 

 is added to autolyzing muscle it experiences the same fate as the 

 creatine originally present, while in one experiment where creati- 

 nine was added in an amount equivalent to the creatine present, 

 it was found to inhibit the usual transformation. This would 

 seem to indicate that the reaction between these two substances 

 is reversible. 



The method employed for the determination of creatinine in 

 muscle is briefly as follows: The finely ground muscle tissue is 

 thoroughly extracted with cold water, and to the extract sufficient 

 alumina cream is added to precipitate the proteins (and enzymes). 

 The mixture is then made up to volume, filtered, and a portion of 

 the perfectly clear filtrate is evaporated with the aid of an electric 

 fan to a sufficiently small volume to make the usual colorimetric 

 estimation. 



The present preliminary experiments are the beginning of a 

 series which are planned upon this problem. 



It is suggested that the above method for creatinine may be 

 of service commercially in ascertaining the age of meat. 



In connection with the present work we have observed that 



1 Loc. cit. 



