THE METABOLISM OF THE CARBOHYDRATES 317 



this sugar, he boiled the mucin-free albumin with strong sulphuric 

 acid. He further stated that the carbohydrate existed in the proteid 

 molecule as a polysaccharide containing nitrogen in its molecule, and 

 which he named " amide cellulosique." 



The more recent methods which have been used to study this 

 carbohydrate group resolve themselves into two classes : in the one 

 of these acid is used to decompose the proteid, and in the other 

 alkali. For the detection of a carbohydrate group in proteid certain 

 colour reactions may also be employed. 



By acting on egg albumin with 10 per cent, caustic potash and 

 neutralising the resulting solution with acetic acid, Pavy was able 

 to obtain, by precipitation with alcohol, a gummy-like mass which 

 itself had no reducing properties, but which when boiled with mineral 

 acids yielded a reducing sugar thought, on account of the melting- 

 point of its osazone, to be dextrose. The gummy-like substance has 

 been further investigated by Fraenkel ( 2 ) (using Ba(OH). 2 instead of 

 KOH), who found it to contain nitrogen and named it Albamin. This 

 worker was able to obtain it also by acting on egg albumin with 

 gastric juice. By the hydrolysis of albamin a reducing monose was 

 obtained. Langstein ( 2> 3 ) prepared a large amount of albamin by 

 the prolonged digestion of egg albumin with gastric juice in the 

 presence of sulphuric acid, and by hydrolysing it he obtained as 

 much as 86 per cent, glucosamin. He thinks it probable that in 

 albamin acetic acid may be present, as in chitin ; he was, however, 

 unable to demonstrate its presence. 



By the action of 3 per cent, hydrochloric acid directly on egg 

 albumin and separation of the reducing substance by means of benzoyl 

 chloride (Miiller's method), Seeman also succeeded in demonstrating 

 the presence of glucosamin, and Langstein, by the same method, has 

 been able to obtain as much as 10 per cent, of this monose from 

 crystallised egg albumin. 



There can be no doubt, then, that, like mucins (and chondro- 

 proteids ?), the most important carbohydrate group in egg albumin is 

 one which yields glucosamin on hydrolysis. 



Langstein has also, by the benzoyl chloride method, separated 

 glucosamin from eu-globulin and cong-albumin in egg white ; and in 

 several other proteids, e.g. fibrin, serum proteids, vegetable albumin, 

 &c., various workers, by the use of phenyl hydrazine, have detected 

 carbohydrate groups. 



No worker has, however, been successful in demonstrating any 

 carbohydrate group in casein, and on this account Pavy has suggested 

 that the lactose of milk really represents dissociated proteid carbo- 

 hydrate. 



