PROTEIN REGENERATION 17 



observation of Embden and Knoop, but at the same time admitted 

 that the evidence adduced for the presence of proteoses and peptones 

 in the blood was not absolutely convincing. Schumm (366) on the 

 other hand was quite unable either in health or disease to detect 

 proteose in the blood. Abderhalden and Oppenheimer (9) held that, 

 if proteose were present, it was present in amount that could not be 

 detected by the ordinary methods ; they therefore maintained that it 

 could not be regarded as a normal constituent of the blood even under 

 the most favourable conditions. For instance, in their experiments 

 three dogs, which had been starved for several days, were given a full 

 meat meal and then killed at the height of digestion and absorption 

 six to eight hours after the meal. On thorough examination ot the 

 blood no trace of a biuret-giving substance could be detected. They 

 put forward the view that the so-called presence of proteose or at 

 least of the biuret reaction was due to the imperfect methods by which 

 the blood was coagulated, i.e. that traces of the coagulable protein 

 were left which sufficed to give a definite biuret reaction. Apart al- 

 together, however, from imperfect coagulation it is possible that the 

 biuret reaction is due to the presence in the blood of non-coagulable 

 proteins or of proteins which can only be coagulated with the greatest 

 difficulty. Such a protein was described by Zanetti (424) who found 

 that, by the addition of a large volume of alcohol to the concentrated 

 filtrate of ox blood, from which all ordinary protein had been removed 

 by careful acidification and boiling, a substance was precipitated which 

 gave all the usual protein reactions. Zanetti held that this body 

 belonged to the class of the mucoids. K. A. H. Morner (289) and 

 Eicholz (112) have also discussed the presence of a mucoid substance 

 in the blood, but do not believe that it is an entity (Morner) but an 

 artifact. Howell (205), however, decides in favour of the serum con- 

 taining a protein which is not coagulable by heat Chabrie's albumone 

 a substance which is neither a proteose nor a peptone. Still more 

 recently Bywaters (84) has also reached the conclusion that the " pro- 

 teose" described in blood is in reality seromucoid. He maintains that 

 the above-mentioned behaviour of the proteoses present in blood agrees 

 with the characteristics of this body. Bergmann and Langstein (63) 

 maintained, however, that the biuret-giving substance was proteose, 

 and that it must be regarded as a constant constituent. Kraus (229) 

 also found that small amounts of proteose could be constantly detected 

 in the blood. As the result of his experiments with hemielastin 

 an elastin proteose Borchardt (67) came to the conclusion that pro- 

 teoses of the food could be found not only in the blood but in certain 



