226 SCIENCE PROGRESS 



effect, as shown by the greater pressor activity of phenyl- 

 ethylamine. The heterocyclic ring in /3-iminazolylethylamine 

 confers great physiological activity on the molecule ; the activity 

 of many complex plant alkaloids doubtless may be referred to 

 the same cause. 



Phenylethylamine, CeH5.CH2.CH2.NH2, is the simplest 

 benzenoid putrefaction base and is of some historical interest 

 as being the first ptomaine that was isolated in the pure 

 state and analysed. Nencki, in 1876, obtained it by allowing a 

 mixture of gelatin with ox-pancreas to putrefy. At first he 

 regarded it as collidine or trimethylpyridine, with which it is 

 isomeric ; subsequently he established its true constitution and 

 considered that it was formed from the amino-acid phenyl- 

 alanine, C 6 H 5 .CH 2 . CH(NH 2 ).COOH, which has since been 

 found in many proteins. 



The other known aromatic amino-acids are tyrosine and 

 tryptophane. The former yields />-hydroxyphenylethylamine 

 which will be considered in a separate section on account of its 

 physiological activity. The amine into which tryptophane is con- 

 verted by the withdrawal of carbon dioxide, 3-fi-Aminoethylindole, 

 has only been obtained quite recently — 



^> 



■^X 



C.CH 2 .CH(NH,).COOH 



r^N 



C.CH,.CH 2 .NH, 



CH 



NH NH 



This base is formed from tryptophane by putrefactive bacteria 

 (Ewins and Laidlaw, Proc. Chem. Soc. 1910, 26, 343) and has 

 been synthesised by Ewins (Joum. Chem. Soc. 191 1, 99, 270) 

 from 7-aminobutyrylacetal and phenylhydrazine. The base 

 has about the same pressor activity as /-hydroxyphenyl- 

 ethylamine but the action is of a somewhat different type. 



p-Hydroxy phenylethylamine. — This base was first prepared 

 without the aid of micro-organisms, simply by heating tyrosine 

 (Schmitt and Nasse, Annalen, 1865, 133, 214), 



OH . C 6 H 4 . CH 2 . CH(NH 2 ) . COOH - OH . C.H, . CH 2 . CH 2 . NH 2 + CO, 



Only a small amount was obtained and the base remained 

 almost unknown during nearly forty years. It was then found 

 to occur naturally by quite a number of investigators. Emerson 

 (Beitr. Chem. Physiol. Path. 1902, 1, 501) separated it from the 

 products of the autodigestion of pancreas and Langstein (ibid. 



