266 PENTOSURIA 



criminate sharply two reducing carbohydrates. One is loosely combined with 

 the nucleins, and in the formation of nucleinic acid separates from nuelein; 

 the second, a firmly combined atomic group with a molecule of nucleinic acid, 

 causes the production of levulinic acid and formic acid, the latter of which 

 does not form a reducing carbohydrate. In view of this, Kossel's adherents 

 admitted the presence of a reducing carbohydrate in animal^ nuelein, but 

 refrained from any expression regarding the nature of the reducing substance. 

 Later, Friedrich Miiller questioned the opinion, then prevalent, that pentose 

 was the sugar of the vegetable kingdom and did not occur in the animal king- 

 dom. He believed there was often a confusion of pentose with glycuronic 

 acid, a confusion which was by no means impossible on account of the test 

 then in vogue. This diversity of views led Bergell and myself to make further 

 researches in regard to pentosuria. From a urine supposed to contain pentose, 

 he and I obtained a barium combination of the questionable sugar, the analysis 

 of which showed we were, in fact, dealing with pentose. By this means, the 

 presence of pentose in the urine of animals was further confirmed by Jastro- 

 witz and Salkowski, and the production by Carl ISTeuberg of pure r-arabinose 

 from so-called pentose urine furnished proof incontestable in every respect. 

 Furthermore, Wohlgemuth, who at my suggestion examined the nucleo-proteid 

 of the liver, produced from this a chemically pure phenylosazone which by 

 analysis proved to be phenylpentosazone. The presence of pentose in animal 

 organs was later confirmed by other competent observers. Thus Neumann, 

 the former co-worker of Kossel, found that, with an improved technic, nucleinic 

 acid obtained from the thymus gland gave a decided pentose reaction. The 

 labors of Bang, Jacob, and Bergell, Friedenthal, Umber, Grund and others, 

 proved the correctness of the theory first suggested by me that not only all 

 vegetables but also all animal nucleo-proteids contained carbohydrates belong- 

 ing to the pentose group. 



The question now arises, How was it possible that these- groups were so long 

 overlooked in the nucleins by prominent investigators, and that my earlier 

 results were so long unconfirmed? This must be ascribed to the fact that in 

 the nucleo-proteid of the thymus, as Umber and I determined in the pancreas 

 proteid, the pentose group is very loosely combined. To obtain the nucleo- 

 proteid of the thymus a solution of the same in an alkali and precipitation with 

 acetic acid are sufficient to separate the greater portion of the pentose and 

 to obtain a phosphorus-containing albumin body that no longer shows pentose 

 but still contains some xanthin bases. And for the nucleo-proteid of the pan- 

 creas Umber has shoflTi that the pentose group is one of the first products of 

 pepsin digestion which enters solution. This view might very readily coincide 

 with that of Kossel's adherents who believe that the reducing carbohydrate 

 is very loosely attached to the nucleo-proteid, for on the solution of thymus- 

 nuclein in alkali a phosphorus-containing albumin body which still contains 

 xanthin bases, i. e., a nuelein, is retained. I believe, therefore, that such a 

 body free from pentose should, at most, be designated an atypical nuelein. 



That the pentose group is but loosely combined with the nucleins is cer- 

 tainly not true of the pancreas nuelein, for Bang has obtained pentose from 

 its nucleinic acid. 



