CERTAIN DERIVATIVES OF THE PROTEIDS. 311 



heating egg-albumin at 160-200 C. with baryta water for 4 to 

 6 days.* Obviously, one cannot draw very sharp comparisons 

 between these several results, but it is quite clear that antial- 

 bumid made from coagulated egg-albumin by the action of 4 

 per cent sulphuric acid at 100 C. yields fully as much tyrosin 

 on decomposition with a strong mineral acid as the mother 

 proteid. Hence the difference in the result when these two 

 substances are treated with active pancreatic juice must be 

 due, not to the lack of the characteristic aromatic group in the 

 antialbumid molecule, but rather to some peculiar state of 

 combination of the atoms or radicles which prevents the for- 

 mation of tyrosin or other amido-acid through the action of 

 trypsin. In the case of antialbumid formed by the hydrolytic 

 action of a dilute acid it might perhaps be claimed that it is 

 purely an artificial product, and that its resistance to the 

 secondary action of trypsin is merely the result of some slight 

 alteration of the original proteid attendant upon the process 

 of cleavage. As opposed to this idea, however, we have the 

 well-known fact that the original coagulated albumin placed 

 directly in alkaline pancreatic juice breaks down step by step 

 to leucin, tyrosin, etc., leaving at the end a large amount 

 perhaps 50 per cent of a peptone (antipeptone) which 

 resembles the peptone resulting from the pancreatic digestion 

 of antialbumid. In other words, there is abundant reason for 

 believing that the so-called anti group is contained as such in 

 the native proteid, and that in the cleavage with dilute 

 sulphuric acid it is split off as antialbumid, while in the pan- 

 creatic digestion of the native proteid it is isolated as anti- 

 peptone through conversion of the so-called hemi groups into 

 amido-acids and nitrogenous bases. 



While it is thus possible to isolate with some degree of 

 purity bodies belonging to or derived from the anti half of the 

 proteid molecule, less satisfactory is the isolation of the so- 

 called hemi bodies. From the amphopeptone f ormed in gastric 

 digestion, the antipeptone can be separated through destruction 

 of the hemi groups, but there is no way known of isolating 

 * See Hermann's Handbuch der Physiologic, v (2), p. 212. 



