THE AMINO ACIDS 



characteristic of putrefaction namely, the amines. 

 Dixon and Taylor in 1907 aroused considerable interest 

 by the publication of their observation that alcoholic 

 extracts of the human placenta when injected intro- 

 venously caused a marked rise in blood pressure and 

 contractions of the pregnant uterus. It was later 

 shown that these phenomena failed to appear in placen- 

 tal extracts free from putrefaction. Evidence was soon 

 produced showing that putrefaction of the placenta 

 caused the production from tyrosine of a new body, 

 namely p-oxyphenylethylamine. This substance was 

 isolated from a pancreas digestion several years pre- 

 viously by Emerson and its production as a product of 

 tryptic action was regarded as unique. In the light of 

 present knowledge there is little doubt that here also 

 it was formed through bacterial agency. This new 

 substance is produced by the liberation of CO 2 from 

 tyrosine, thus : 



OH 



OH 



ICOOJH 

 Tyrosine 



p. oxyphenyl-ethylamme 



