250 DEFENSE AGAINST NON-ANTIGENIC POISONS 



U 11 



A'=C\ H H H 



HCC J>C—C^ /C=C\ OH 



V — Cf >CH + = HCC \C — Ca 



H V = r^ V — cf )CH 



H H H \C=C^ 



H H 



(iiaphtlialiii) (a-iiaplitliol) 



The same is the case with mam- camphors and terpenes. Reduction 

 may be the preliminary step, as with chloral hydrate, which is first 

 reduced to trichlor-ethyl-alcohol. In still other cases splitting off of 

 w^ater is the chief preliminary step. 



3. Glycocoll is one of the longest known combining substances, the 

 observation of the combination of glycocoll with benzoic acid to form 

 hippuric acid being the first proof of synthesis in the animal body dis- 

 covered by Wohler (1824). The reaction is as follows: 



C„H,,COOH + H,N-CHo-COOH = aH-,CO — HN-CH„-CnOH. 

 (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. ]\Iany 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., toluene is oxidized to benzoic acid, xylene to toluic 

 acid, nitro-benzaldehyde to nitro-benzoic acid. INIany of the sub- 

 stances 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 sul- 

 phuric and glyeuronic acid reactions, combination occui*s whenever a 

 suitable substance is present in the blood, glycocoll always being abun- 

 dant as a cleavage product of the proteins. 



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. — IMothylation, which occurs also with tellurium, is 

 observed on administration of pyridine, as shown by the following 

 equation : 



This reaction is of special importance, because many alkaloids contain 

 a pyridine group ; and the resulting methyl compound may be less 

 toxic than the original alkaloid — e. g., methyl mori)hine. 



