go J. L. ROSEDALE 



desired to compare the muscle protein of several animals with a view to more 

 complete data at a later time. A comparison of these results with those by 

 Kossel's method has been made in a few cases. The results indicate that 

 differences exist in the amino-acid content of the various muscle proteins. 

 Duplicate analyses were always carried out; frequently these analyses were 

 not so concordant as was expected. This inconsistency of the results was 

 under investigation by Plimmer [1916] who tested the arginine determination; 

 other details of the method are now being studied. 



Experimental. 

 In the case of the smaller animals (rabbit, chicken) opportunity was taken 

 of comparing the flesh of different parts of the body of the same animal. In 

 other cases the flesh was taken from the thigh. The mode of operation was 

 the same throughout. The flesh (about 350 g.) was freed from inside fat, 

 minced and put into about 2 litres of boiling water containing 0-1 % acetic 

 acid and heated for about ten minutes so as to coagulate the protein and 

 remove the extractives. The liquid was poured off and the coagulated protein 

 squeezed dry in a cloth. This procedure was repeated twice. The coagulated 

 protein (about 200 g.) was then digested with 1 g. pepsin in 2 litres of 

 0-liV HCl, so as to separate nucleins, indigestible matter, etc. After digestion, 

 which usually occupied about ten days at 37° the liquid was filtered off and 

 the total nitrogen estimated. A portion containing about 6 g. of protein was 

 then hydrolysed by boiling with hydrochloric acid added to the liquid so as 

 to make a concentration of 20 %. The hydrolysis was carried on for 36 hours. 

 The hydrolysed solution was evaporated to dryness in vacuo, made up to 

 250 cc. and two samples of 100 cc. were analysed by Van Slyke's method. 

 This was performed as described except for the arginine estimation which 

 was effected by Plimmer's modification [1916]. In the earlier experiments it 

 was impossible to make determinations of amide N owing to the facilities for 

 vacuum distillation not being adequate. The analyses were made in duplicate 

 and the percentage has been calculated from the average. 



Table I. Nitrogen percentages. 



Relatively little difference can be observed from the figures for the different 

 meats. The amide N is almost similar, in each case averaging about 6-0 % 

 of the total N. 



