428 SCIENCE PROGRESS 



Kuhne himself and one of his pupils, Chittenden, disturbed 

 it seriously by ascertaining that his hemi-albumose, comprising 

 half the original globulin on his hypothesis, was a mixture of 

 at least three albumoses, with another substance of very 

 indigestible character in small proportion. These three 

 albumoses, known as proto-, hetero-, and deutero-albumoses 

 were shown to be quite different from each other in many 

 respects, and not to stand upon the same level as each other, 

 as the theory demanded that they should. The formation of 

 the albumoses was successive and not simultaneous. When 

 proto- and hetero-albumoses were submitted to the action of 

 pepsin they formed deutero-albumose before, or coincidently 

 with, peptone. 



When the three albumoses were further examined, neither 

 was found to be a pure hemi-product. Nor was anti-albumose 

 much like hemi-albumose in its reaction ; indeed, it soon became 

 doubtful whether it could properly be called an albumose at 

 all. There was little or no evidence of its occurring during 

 digestion, as it should do in considerable amount if the cleavage 

 hypothesis were correct. 



When the further stage of cleavage by trypsin was scrutinised* 

 the albumoses of the hemi-group were not found to behave 

 as the theory required. Both proto- and hetero-albumose were 

 found to give rise to a certain amount of anti-peptone and to 

 amino-acids, but in the case of the proto-albumose the latter 

 were the chief products, while in that of the hetero-albumose 

 the anti-peptone was in excess. 



Kiihne's.hemi-peptone has not been proved to occur during 

 digestion — its existence, in fact, is somewhat hypothetical. No 

 hemi-compound seems to occur under the action of trypsin, so 

 that if such a body is formed it is at once split up into the 

 amino-acids. 



Besides these critical objections raised against Kiihne's 

 hypothetical scheme of proteoclastic decomposition, a more 

 theoretical one may be advanced, based upon the probability 

 that the zymolytic breaking up of large molecules would be 

 comparable in different cases. In the case of the action of 

 diastase on starch we have undoubtedly a gradual decomposition 

 of the complex molecule of the substrate, marked by the 

 successive appearances of members of the amyloin or malto- 

 dextrin groups of substances, closely resembling each other and 



