ORGANIC POISONS 163 



The same is the case with many camphors and terpenes. Re- 

 duction may be the preliminary step, as with chloral hydrate, 

 which is first reduced to trichlor-ethyl-alcohol. In still other 

 cases splitting off of water is the chief preliminary step. 



3. Glycocoll is one of the earliest known combining sub- 

 stances, the observation of the combination of glycocoll with 

 benzoic acid to form hippuric acid being the first proof of syn- 

 thesis in the animal body discovered by Wohler (1824). The 

 reaction is as follows : 



C 6 H 5 COOH + H 2 N - CH 2 - COOH = C 6 H 5 CO HN - CH 2 - COOH. 



(benzoic acid) (glycocoll) (hippuric acid) 



A special enzyme has been found in kidney substance which can 

 bring about this reaction outside the body. Normally this 

 enzyme occurs chiefly in the kidney but may also occur in other 

 organs. Many other aromatic compounds also combine with 

 glycocoll before elimination, e. g., salicylic acid. Some are first 

 altered to a suitable form by oxidation ; e. g., toluol is oxidized 

 to benzoic acid, xylol to toluic acid, nitro-benzaldehyde to nitro- 

 benzoic acid. Many of the substances that can be made to 

 combine with glycocoll in the body are of such a foreign nature 

 that they never could need neutralization under any other than 

 experimental conditions, but here, as with the sulphuric and 

 glycuronic acid reactions, combination occurs whenever a suit- 

 able substance is present in the blood, glycocoll always being 

 abundant as a cleavage product of the proteids. 



4. Urea may also be a means of defense, forming salts with 

 organic acids which are rapidly eliminated ; e. g., amido-benzoic 

 acid and nitro-hippuric acid. 



5. Methane. Methylation, which occurs also with tellurium, 

 is observed on administration of pyridin, as shown by the fol- 

 lowing equation : 



H H H H 



X.C-CL ^- c ^ / CH 3 



HCf >N + CH 4 + O = HOT >N< 



\C-:C / XJ=(/ X OH 



H H H H 



(pyridin) 



This reaction is of special importance, because many alkaloids 

 contain a pyridin group; and the resulting methyl compound 

 may be less toxic than the original alkaloid e. g., methyl mor- 

 phine. 



6. Sulphur split off from proteids may combine with CNH 

 and CNK, converting them into the much less toxic sulpho- 

 cyanides. 1 



1 See Meurice, Arch. int. Pharmacodyn., 1900 (7), 11. 



