CARBOHYDRATES. 33 



seemed probable that the glucuronic acid was formed from decomposed 

 albumin. According to recent investigations concerning the reserve 

 stores of sugar in the starved organism, especially of glycogen, all such 

 conclusions have become doubtful. Furthermore, the whole question 

 of the formation of glucuronic acid from albumin coincides with that of 

 carbohydrates from proteins. At another place we shall discuss this 

 problem in detail. On the other hand, an observation made by Salkowski 

 and Neuberg 1 is worthy of mention here. They found that glucuronic 

 acid when exposed to intense putrefaction goes over into the aldopentose, 

 l-xylose, with the splitting off of carbonic acid. 



CHO COH 



HCOH HCOH 



HOCH HOCH 



HCOH HCOH 



HCOH H 2 COH 



io. 



OH 

 d-Glucuronic acid Z-Xylose 



We have met with Z-xylose before. It is found in the nucleoproteids of 

 the pancreas and liver, and is perhaps the sole pentose occurring in the 

 animal organism. This observed transformation connects the aldo- 

 hexose, glucose, with the aldopentose, xylose. It is indeed conceivable that 

 the formation of xylose in the animal system may take place in a similar 

 way. For the present we have no precise knowledge about this process, 

 and we know just as little regarding the place of formation of glucuronic 

 acid, i.e., in what part of the body the compound is synthesized. It is 

 extremely probable that it is not limited to a single organ. 2 



Glucuronic acid is to be considered as a substance which protects the 

 organism against the action of various kinds of substances some of which 

 are formed in the body while some are brought into contact with the cells 

 of the body from the outside. It combines with these substances and 

 makes them harmless. We shall subsequently meet with other compounds 

 (glycocoll, sulphuric acid) which perform the same task. The poisons 

 thus neutralized are almost always substances which cannot be destroyed 

 in the organism by direct oxidation. Glucuronic acid may combine 

 directly with these poisons, that is, without the latter undergoing any 



1 Z. physiol Chem. 36, 261 (1902). 



2 Julius Pohl: Arch. exp. Path. Pharm. 41, 97 (1898). 



