136 HUMAN PHYSIOLOGY 



The changes brought about by the putrefaction are, in 

 many respects, similar to those produced by digestion ; in 

 other respects, they are very different. 



From proteids there arise by putrefaction : 



1. Albumoses and peptones. 



2. Fatty acids, amido-acids, and ammonia; by the putre- 

 faction of gelatin, glycocoll is also formed. 



3. Phenol, paracresol, indol, skatol, phenylpropionic 

 acid, phenylacetic acid, paraoxyphenyl-acetic acid, paraoxy- 

 phenyl-propionic acid. 



Indol, C g H 7 N, has the following constitution: 







\NH/ 

 Skatol, C 9 H 9 N: 



C . H /C 



\ NH 



Part of the aromatic products of proteid putrefaction are 

 absorbed; they are then in part oxidized (indol forming indoxyl, 

 skatol forming skatoxyl). The aromatic oxy-acids are not 

 changed, but phenol, indoxyl and skatoxyl are excreted by the 

 urine as conjugated sulphates. 



4. Gases: carbonic acid, hydrogen, marsh gas, and sul- 

 phuretted hydrogen. 



Putrefaction, therefore, like tryptic digestion, forms pro- 

 teoses and amido-acids from proteids. But by putrefaction 

 there are also formed aromatic decomposition products 

 (phenol, oxy-acid, indol, and skatol), which are not formed 

 by the action of trypsin. 



Fats are split into fatty acids and glycerin by putrefaction. 

 The fatty acids are in part still further decomposed into the 

 lower fatty acids. 



From the carbohydrate, alcohol, lactic, acetic, and suc- 

 cinic acids are formed by putrefaction. Part of the starch is 

 first changed to sugar. The indigestible cellulose is also 

 acted upon by putrefaction ; this, however, does not form 

 sugar but organic acids (acetic, valerianic acid, etc.), car- 

 bonic acid, and methane. By this decomposition of the 



