iv THE CARBOHYDRATE-RADICALS 155 



hydrate, must be contained in albumins, has been asserted for a long 

 time. Berzelius l came to this conclusion because certain decomposition- 

 products, such as humin, saccharic and oxalic acids, are common to 

 both albumins and carbohydrates ; subsequently, in confirmation of 

 his view, he showed that the furfurol reaction is not only characteristic 

 for carbohydrates, but for all albumins. Kossel, Blumenthal, and 

 others found pentoses and other carbohydrates amongst the dissocia- 

 tion-products of the nucleo-proteids ; these were derived, however, not 

 from the albumin-moiety, but from the nucleic acid radical. The first 

 definite proof as to the existence of carbohydrate-groups in proteids 

 we owe to Eichwald, 2 who discovered a carbohydrate in mucin. This 

 line of research was then taken up by Hammersten, who was, however, 

 so little inclined to believe that the carbohydrate formed a part of 

 the proteid-molecule, that he classed mucins and similar substances 

 together as compound glycoproteids to distinguish them from ordinary 

 proteids. Only after Pavy 3 had prepared from what he considered 

 to be a pure albumin, namely, egg-white, the osazone of a hexose, was 

 this whole question discussed with more interest. Within the last 

 ten years much work has been done in this field, but one complication 

 arose which made progress very difficult, for the formation of sugar 

 from proteids during metabolism, and particularly in cases of diabetes 

 mellitus, has repeatedly been mixed up with the simple problem, or 

 at least has been connected with it (Cohnheim.) 



Such confusion is, however, quite unjustifiable, as has been pointed 

 out by Miiller, 4 Seeman, 5 and Muller and Seemann, 6 for the amounts 

 of the carbohydrates in albumin are far too small in proportion to 

 the sugar so produced. 



The most important fact, from the physiological standpoint, is the 

 conversion of a great portion of the carbon of the albumin into 

 dextrose or glycogen. 7 Leucin, which Fr. Miiller, 8 Cohn, 9 and others 

 have thought of in this respect, is a derivative of isocaproic acid, 

 and therefore would have to undergo a preliminary and complicated 



1 According to N. Krakow, Pflugers Arch. 65. 282 (1897). 



2 Eichwald, Ann. d. Chem. und Pharmac. 134. 177 (1865). 



3 Pavy, Physiology of Carbohydrates, 1895. 



4 Friedrich Muller, Zeitschr. f. Biolog. 42. 468 (1901). 



5 Seemann, Uber d. reducierenden Suhstanzen, welche sich aus Hiihnereiweiss 

 abspalten lassen : Inaugural Dissertation, Marburg, 1898. 



6 F. Muller and J. Seemann, 'Uber die Abspaltung von Zucker aus Eiweiss,' D. 

 med. Woschenschr. , 1899, Nr. 13, p. 209. 



' M. Cremer, Ergebnisse der Physiologic, by Asher and Spiro, 1. 803 (1902) ; Roily 

 Deutsch. Arch. f. klin. Med. 78. 250 (1903). 



8 Fr. Muller, Zeitschr. f. Biol. 42. 468 (1901). 



9 R. Cohn, Zeitschr. f. physiol. Chem. 28. 211 (1899). 



