a86 Biological Chemistry. 



the chemical mechanism by means of which the decom- 

 position of the complex ingestion products is brought 

 about in the body. If the case of a simple carbohydrate 

 such as dextrose is considered, it will be found that its 

 final metabolism products consist of carbon dioxide and 

 water. It is not to be supposed that the oxidation of 

 this substance can be represented by the simple equation 



C 6 H ]2 6 + 60 2 = 3C0 2 + 6H.O 



without the formation of some intermediary products ; in 

 fact, if certain substances foreign to the body, such as 

 camphor, chloralhydrate, and certain aromatic substances, 

 are ingested, they are excreted conjugated with glycuronic 

 acid,* CHO(CH (OH)) 4 - COOH, which is one of the first 

 oxidation products of dextrose. It is not unreasonable to 

 suppose that this acid is formed in the body as a normal 

 oxidation product, and that in the presence of foreign 

 substances with which it can enter into chemical reaction 

 it forms compounds which will not undergo further oxida- 

 tion, but are eliminated from the organism in the urine. 

 Intermediary oxidation products can even be isolated from 

 such simple substances as methane when the combustion 

 is carried out under suitable conditions. Thus Bone has 

 shown that formaldehyde can be identified at an early stage 

 in the decomposition of methane, the complete combustion 

 of which can be represented in the following way : 



CH 4 -> CH 3 (OH) CH 2 (OH) 2 > CH,0 > 1^ 

 + CO-- >H 2 + C0 2 



In the following pages a short account will be given of 

 some of the methods which have been employed for in- 

 vestigating the stages through which the ingesta pass in 

 the course of their degradation through the various organs, 



* That is, as compounds formed from glycuronic acid by the elimination of 

 the elements of water from glycuronic acid and the substance. 



