38 



THE AMINO ACIDS 



tion of the substances characteristic of putrefaction is 

 readily understood. The amino acids which are espe- 

 cially susceptible to bacterial action are tyrosine and 

 tryptophane. From tyrosine a whole series of com- 

 pounds may be formed and are regularly present as 

 putrefactive products, as for example, paroxyphenyl- 

 propionic acid (hydro-paracumaric acid), and paroxy- 

 phenylacetic acid (also phenylpropionic and phenyl- 

 acetic acids), as well as paracresol and phenol. The 

 relationships are readily seen from the following 

 formulae : 



OH 



o 



OH 



OH 



CH 9 



CH.NH, 



I 

 COOH 



Tyrosine, or 



p. oxy-phenyl 



o-amino-propionic 



acid 



OH 



COOH 



p. oxy-phenyl 



propionic 



acid 



p. oxy-phenyl 



acetic 



acid 



OH 



Phenol 



