IV 



THE CARBOHYDRATE RADICALS 159 



Cathgart 1 ), which is a further proof that it has nothing to do with the 

 formation of sugar out of albumins. The mucin obtained from frog's 

 spawn contains, according to Schulze and Ditthorn, galactosamin 

 instead of glucosamin. 



This glucosamin is, however, not contained in the mucins as such, 

 but in a more complex form. If mucin is boiled with strong acids, as 

 in preparing amino-acids, only little or no carbohydrate is found ; it is 

 apparently destroyed, being entirely converted into humin or mela- 

 noidin, as Langstein 2 has shown. Miiller obtained larger quantities 

 of glucosamin, only, by boiling for a short time with dilute hydro- 

 chloric acid, the greatest yield being obtained by boiling for three to five 

 hours with 2 '5 per cent hydrochloric acid. The mucin is, however, not 

 completely destroyed by this process, there being formed albumoses and 

 peptones, which make the extraction of the carbohydrate very difficult. 

 The carbohydrate is, however, not attached to any of the proteid- 

 radicals, as these peptones and albumoses may be got rid off by 

 phosphotungstic acid (Steudel), or iron acetate and tannic acid (Miiller). 



The largest yield is obtained, according to Seeman and Langstein, 3 

 when the proteid is allowed to swell up into a jelly with an alkali, and 

 is then dissociated with an acid. Glucosamin obtained by dissociating 

 glyco-proteids with acids, has these properties : It reduces, but it does 

 not contain any free NH 2 - groups, as Steudel failed to couple it with 

 phenyl-cyanate till he had previously heated the compound with 

 sulphuric acid under pressure. Leathes has therefore assumed that a 

 second carbo-hydrate is attached to the nitrogen, analogous to the 

 coupling of atoms in chondrosulphuric acid, as held by Schmiede- 

 berg; 3 Neuberg and Heymann failed, however, to demonstrate a 

 second carbohydrate, and they deny the correctness of Leathes' views ; 

 glycuronic acid they also excluded. 



Ledderhose found in chitin, Miiller in mucin, and Schmiedeberg 3 

 in chondrosulphuric acid, prepared from chondromucoid, acetic acid 

 constantly in combination with glucosamin. As Miiller further 

 observed that diacetyl-glucosamins give Ehrlich's dimethyl-^-amino- 

 benzaldehyde reaction (see p. 10), it is very well possible that the 

 body which is liberated from mucins is at first a diacetyl-glucosamin, 

 especially as penta- and mono-ace tyl-glucosamins do not give the 

 colour reaction of Ehrlich. 



In egg-white, glucosamin is not contained as such, because, accord- 

 ing to Steudel, it does not at first combine with phenylcyanate. 



1 Pr. Cathcart, Zeitschr. f. physiol. Ghent. 39. 423 (1903). 



2 L. Langstein, ibid. 31. 49 (1900). 

 3 0. Schmiedeberg, Arch.f. experiment. Path. u. Pharmakol. 28. 355 (1891). 



