328 J. HOWARD MUELLER 



It is apparent that the reactivating material will withstand 

 fairly thorough acid hydrolysis, and is, therefore, probably, but 

 not necessarily, not of a polypeptid nature, since it is known that 

 protein hydrolyzed in this way is not completely reduced to the 

 amino acid stage. 



The further possibihty exists that the reactivating material is 

 not connected with the protein molecule at all, but is present as 

 an impurity. If casein is reprecipitated several times from so- 

 dium carbonate solution, by means of acetic acid and the resulting 

 product washed thoroughly by alcohol and ether, the "pure" 

 casein so obtained will yield a hydrolysate which is just as active 

 as that from crude commercial casein. It cannot, perhaps, be 

 justly concluded from this experiment that the activating material 

 is in fact a part of the protein molecule, for, as Funk (1920) has 

 suggested, it may equally well be explained on the basis of a 

 quantitative adsorption of the material from solution by the 

 casein during precipitation. Since the material is known to be 

 adsorbed quantitatively by charcoal, it is not impossible that it 

 may also be taken up by other finely di\'ided precipitates, al- 

 though it is not adsorbed by such precipitates as BaS04, metallic 

 sulphides, etc., as will appear later. For the present, we must 

 await further evidence to show whether the substance is of 

 protein or non-protein origin. 



Since many of the experiments reported in the first paper of 

 this series had shown that meat infusion was a rather difficult 

 material to work with chemically, and since there are a number 

 of fairly standardized methods for the partial separation of the 

 amino acids in protein hydrolysates, the simpler experimental 

 course seemed, at the time these preliminary observations were 

 made, to attempt the separation and identification of the activat- 

 ing material from such protein hydrolysates. The possibihty 

 of re-extracting the material from the charcoal was considered, 

 but since about 20 per cent of the total soUds of the heart in- 

 fusion are removed by charcoal under these conditions, it seemed 

 probable that even though a method for re-extracting from the 

 charcoal could be de\ised, the extract might contain a somewhat 

 complex mixture of compounds difficult to characterize and work 



