ORGANIC NITROGEN. ITS DECOMPOSITION. 53 



earlier form, and consequently its atoms must enter into new relations 

 to form new bodies. These by-products have not been actually in the 

 bacteria and are not the direct results of metabolism. The new 

 products formed in the decomposing mass are partly gaseous. 

 This is proved by the odor that commonly arises from putrefying 

 bodies which are indications of the exhalation of volatile products. 

 A chemical study has shown, in many cases, the actual nature of 

 these gaseous products, indicating that the end-products are 

 chiefly CO 2 , H, CH 4 , NH 3 , H 2 S, and N, in addition to others, present 

 in much smaller amount, producing the peculiar and characteristic 

 odors. Some of the new products are solids and may be either 

 soluble or insoluble. If soluble they are dissolved in the course 

 of time by the rain which falls upon the decaying mass and pass 

 into the soil, perhaps to be drained away in the drainage-water. 

 The insoluble bodies are also incorporated into the soil, becoming 

 eventually mixed with the solid masses of the earth. 



The list of the by-products of such decompositions is a long one. 

 A few of these are as follows : Carbon 'dioxid, hydrogen sulphid, 

 marsh gas, hydrogen, nitrogen, calcium carbonate, propionic acid, 

 valerianic acid, acetic and lactic acids, alcohol, succinic acid, 

 phenol, indol, leucin, tyrosin, skatol, etc. 



This list is far from complete. It includes only a few of the 

 products already known, and beyond question there are numerous 

 bodies, formed as by-products or excretions, which still remain 

 to be discovered. The actual products which appear will depend 

 upon three factors: (i) The substance which is decaying; (2) 

 the species of bacteria which produces the decay; (3) the conditions 

 under which the decay occurs. 



The Ammoniacal Fermentation. One phase of these decom- 

 position processes must be especially mentioned. After passing 

 through an unknown series of intermediate stages, the nitrogen 

 of the decaying mass assumes, in large part, the condition of 

 ammonia. One of the first and easiest substances to undergo 

 this ammoniacal fermentation is urea. Urine is always filled 

 with bacteria, even while in the ducts from the bladder, and among 

 them are several species that cause it to break down to form ammonia 



