316 THE METABOLISM OF THE CARBOHYDRATES 



Orgler and Neuberg ( 5 ), in a recent publication, have, how- 

 ever, cast doubt on the presence of glucosamin in chondrosin, 1 for 

 they have succeeded in isolating from the decomposition products 

 of chondrosin sulphate, a copper salt of tetraoxyaminocaproic acid 

 (C 6 H 7 O 2 (OH) 4 NH 2 ) 9 Cu, with which, in chondrosin, they show it to 

 be impossible that glucosamin can be combined. They conclude 

 this from a comparison of the formulae of chondroitin-sulphuric acid 

 and tetraoxyamincaproic acid, and also from their inability to detect 

 glucosamin or any related, body in the decomposition products of 

 chondrosin. 2 



In mucin and mucoid it has for many years been known that 

 reducing substances are present. In the fluid from an ovarian cyst, 

 Scherer, in 1852, discovered a proteid, which he named metalbumin, 

 and which by boiling with weak acid yielded a reducing substance. 

 It has since been established that Scherer's metalbumin is mucin. 

 The most exhaustive work on the carbohydrates in mucin, &c., is by 

 Friedrich Miiller and his pupils ( 2 ). The method used by these 

 workers consisted in hydrolysjng the mucin with H 2 SO 4 . To the 

 resulting solution (with or without previous separation of proteids) 

 benzoyl chloride and caustic alkali were added, whereby a precipitate 

 of the benzoyl ester of the sugar was obtained. By a determination 

 of the melting-point and crystal form of this compound and by its 

 elementary analysis, the exact nature of the carbohydrate was ascer- 

 tained. In this way, it was found that sputum mucin, stomach mucin, 

 ovo-mucin, and pseudo-mucin contained glucosamin. So far, no other 

 carbohydrate than this has been discovered in mucin, and it is 

 probable that here, as in chitin, the glucosamin is combined with 

 acetic acid. 



In the nucleo-proteids obtained from the pancreas, thymus, 

 thyroid, spleen, muscles, &c., there has been found, by Hammer- 

 sten and others, to be constantly present a pentose group which 

 can be dissociated from the nuclein molecule by the action of 

 acids. The exact variety of this pentose in the nucleo-proteid 

 of the pancreas and liver has been shown to be Z-xylose. Certain 

 nucleo-proteids, e.g. of the thymus gland and of yeast, also contain 

 hexoses, for, as Kossel has shown, they yield laevulinic acid 

 amongst their decomposition products, and this can only come from 

 hexoses. 



It is with regard to true proteids that the most interesting results 

 have been obtained. Schutzenberger was the first to draw attention 

 to the presence of a reducing sugar in egg albumin. To liberate 



1 Ba(OH) 2 was employed as decomposing agent. 



2 Glycuronic acid also cannot be present. 



