THE CARBOHYDRATE RADICALS 157 



Miiller l and his pupils, 2 Frankel, 3 Mitjukoff, 4 and others, have shown. 

 Some other substances belong also to this group, namely, the glyco- 

 proteid of Helix and ichthulin, which Hammarsten classed together 

 with the glycoproteids, and further, the mucilagenous envelope of 

 frog's eggs, 5 the coverings of the eggs of Sepia and Loligo, 6 and the 

 ground substance of gelatinous sponges. 6 Amongst invertebrates similar 

 substances are probably widely distributed. 



All we knew at first about the nature of this carbohydrate 

 was that albumins, on being boiled with acids, split off a body which 

 reduced cupric oxide in an alkaline solution, i.e. which gave Trommer's 

 test, or one of the modifications of the latter. Subsequently all 

 .^kfearches aimed at isolating an osazon, which could then be identified, 

 >y comparing its melting point and its composition with those of one 

 f the known mono- or di-sacharides. The fact was established that 

 the carbohydrate which could be isolated from mucins and eventu- 

 ally from other proteids was a hexose, and that in all probability 

 it was dextrose. Eichholz, 7 Blumenthal, 8 and Mayer 9 prepared a 

 glycosazone having the characteristic melting point of 202 to 

 204. 



The real state of matters was first discovered by Friedrich Miiller. 1 

 There is contained in mucin a glucosamin, i.e. a nitrogen-containing 

 derivative of dextrose. As this compound gives the same osazone as 

 does the non-aminated hexose, all the older statements, made by 

 different observers, retain their value. The existence of this gluco- 

 samin amongst the dissociation-products of the mucins and mucoids has 

 been confirmed, in addition to M-iiller's pupils : Weydemann, 2 Seemann, 2 



1 F. Miiller, 'Schleim der Respiratiousorgane,' Sitzungsber. der Oes. z. Beford. d. 

 ges. Naturw. zu Marburg, 1896, p. 53; 1898, p. 117; Zeitschr.f. Biol. 42. 468 (1901). 

 (This paper contains a complete summary of the work done by Miiller and his 

 pupils.) 



2 H. Weydemann, Tierisdies Gummi aus Eiweiss : Dissert., Marburg, 1896 ; J. 

 Seemann, Reduzierende Substanzen o,us Huhnereiweiss : Dissert., Marburg, 1898; 

 Ziingerle, Munch, medizin. Wochenschr., 1900, Nr. 13. 



3 S. Frankel, ' Spaltungsprodukte des Eiweiss bei der Verdauung,' Monatsh.f. Chem. 

 19. 747 (1898). 



4 K. Mitjukoff, Dissert., Bern ; Arch. f. Gynakologie, 49. fas. 2, 1895. 



5 F. N. Schulz and F. Ditthorn, Zeitschr. f. physiol. Chem. 29. 373 (1900), 32. 

 428 (1901). 



6 0. v. Flirth, Hofmeister's Beitrdge, 1. 252 (1901). 



7 A. Eichholz, ' The Hydrolysis of Proteids,' Journal of Physiology, 23. 163 

 (1898). 



8 F. Blumenthal and P. Mayer, Berichte d. deutsch. chem. Gesellschaft, 32. L 274 

 (1899). 



9 P. Mayer, Deutsche med. Wochenschr. 1899, Nr. 6, p. 95. 



