CLEA VAGE THEOR Y OF PROTEID DIGESTION. 417 



. It will be seen from this that the term hemipeptone is 

 a term for something which has a separate existence only in theory. 

 There has as yet been no method either devised or fallen upon by 

 accident of separating these two substances which are supposed by the 

 cleavage theory to be present, mixed in equal proportions, in ampho- 

 peptone. This is somewhat remarkable, in view of the number of years 

 the theory has now been in vogue, and the large amount of experimental 

 work that has been carried out in connection with it, and ought to be 

 looked upon as an indication, either that amphopeptone is not really 

 a mixture of antipeptone with a hypothetical hemipeptone, but a 

 substance capable of breaking up under the action of trypsin into a new 

 peptone (antipeptone) and a number of amido -compounds ; or that anti- 

 and hemipeptones are not separately present in amphopeptone, but that 

 this peptone breaks up upon the further action of trypsin into antipeptone 

 and hemipeptone, and that this hypothetical hemipeptone is next acted 

 upon and broken into simpler bodies, finally yielding leucine, tyrosine, 

 and the other companions of antipeptone found in complete tryptic 

 digestion. 



The decomposition of proteids by trypsin is represented by 

 Neumeister l according to the following schema : 



Proteid. 



Deuteroalbumose 

 Amphopeptone 



Antipeptone Hemipeptone 



I I I I 



Leucine Tyrosine Aspartic Acid Tryptophan, etc. 



According to the same author, several deuteroalbumoses are formed, in the 

 course of tryptic digestion, yielding corresponding amphopeptones. He also 

 states that all the albumoses, up to the present known, whether formed in 

 peptic or tryptic digestion, are amphoalbumoses, that is to say, yield both 

 antipeptone and amido-acids on complete tryptic digestion. The ratio between 

 the amounts of antipeptone and of amido-acids is a very variable one ; 

 heteroalbumose, for example, yielding much antipeptone and little amido-acid, 

 while protoalbumose breaks up into much amido-acid and very little anti- 

 peptone. Those who hold the cleavage theory explain this by saying that 

 heteroalbumose is to a large extent an anti-substance, and protoalbumose 

 almost purely a hemi-substance ; but the experimental facts may be met 

 equally well by the statement, that heteroalbumose is an albumose of such a 

 chemical nature that it breaks up under the action of trypsin so as to yield a 

 large percentage of peptone unalterable by further action of trypsin, accom- 

 panied by a small amount of amido-acids; protoalbumose is an albumose 

 different in nature from heteroalbumose, and yielding, on further tryptic 

 digestion, very little peptone (antipeptone) and a large amount of the amido- 

 acids. There is no more proof that either heteroalbumose or protoalbumose is 

 such a mixture of albumoses as the cleavage theory demands, than there is 

 that amphopeptone is such a mixture of the corresponding peptones. 



All the observed facts of peptic and tryptic digestion may be simply 

 represented by the following schema, without any reference to the 



1 "Lehrbuch der physiologischen Chemie," Jena, 1893, Th. 1, S. 200. 

 VOL. I. 27 



