108 THE DUCTLESS GLANDS 



It has recently been shown that the iodine reaction, the 

 mercuric chloride reaction, and the bi-iodate reaction are due 

 wholly or in part to oxidation. Potassium persulphate was 

 found by Ewins to have a similar oxidizing action upon adrenin, 

 giving a characteristic red colour. This reaction is stated to 

 have advantages over those mentioned above both in sensitive- 

 ness and in being readily obtained with crude extracts of 

 chromaphil tissues. The mercuric chloride reaction appears 

 to be due to the oxidation of adrenin by such oxidizing agents 

 as mercuric chloride, silver nitrate, or platinic chloride under 

 the catalytic influence of salts of metals with " weak " acids 

 (i.e., salts which are hydrolytically dissociated by water). 

 The reaction may be compared with the results which have 

 been obtained in the investigation of certain " laccases." The 

 characteristic colour reactions of adrenin are given by certain 

 other closely related bases namely, by (a) the amino base, 

 corresponding to adrenin ; (6) dihydroxyphenylethylamine 

 and the corresponding methyl, ethyl, and propylamino bases ; 

 (c) amino-aceto pyrogallol. The bases of the type amino-aceto 

 catechol do not give these reactions (Ewins). 



The physiological action of adrenin, an action simulating 

 that of the true sympathetic nervous system, is possessed also 

 by a large series of amines, the simplest being primary fatty 

 amines. Barger and Dale describe all such amines and their 

 action as " sympathomimetic." They find, as the result of a 

 careful investigation, that the more nearly the structure of an 

 amine approaches to that of adrenin, the more intense and the 

 more specific is its sympathomimetic action. All the chemical 

 products which possess this specific action are primary and 

 secondary amines. The quaternary amines corresponding to 

 the aromatic members of the series have an action closely 

 similar to that of nicotine. There are two optimum conditions 

 of chemical structure in which the action is most pronounced. 

 The first is a benzene ring with a side-chain of two carbon 

 atoms, the terminal one bearing the amino group. The second 

 is the presence of two phenolic hydroxyls in the 3 : 4 position 

 relative to the side-chain ; when these are present an alcoholic 

 hydroxyl still further intensifies the activity. A phenolic 

 hydroxyl in the 1 position does not increase the activity. 



As a practical result of these investigations 3 : 4 dihydroxy- 

 phenylethylmethylamine, one of the most active of the sympa- 



