Cellulose Ferments 343 



tract of herbivorous animals might also have its origin 

 in the cellulose of the food. 



Not long afterward it was demonstrated that the 

 production of marsh gas in the animal system is due to 

 certain microorganisms present in very large numbers 

 in the large intestine and capable of setting up cellulose 

 fermentation. This fermentation is accompanied by 

 the formation of soluble substances assimilated by the 

 animals, and also of gaseous products, including carbon 

 dioxid and marsh gas. The cellulose ferments in the 

 animal intestine may be thus regarded as a distinct aid 

 in the digestive processes of their host. 



The cellulose in the solid excreta and the litter under- 

 goes further fermentation in the manure pile. Indeed, 

 it has been pointed out that cellulose fermentation in 

 the latter may be regarded as a continuation of the same 

 process in the intestinal tract. In the interior of the 

 heap, these processes proceed very rapidly, leading to 

 the familiar crumbling of the woody material and the 

 entire disappearance, under favorable conditions, of the 

 coarse portions of the uneaten food and of the litter. 



Gases in the manure pile. The analysis of the gases 

 in the manure pile shows that the destruction of the 

 cellulose takes place largely in the deeper layers where 

 the air is almost entirely excluded. Gases taken by 

 Deherain from different parts of the heap showed the 

 following composition: 



Carbon dioxid Oxygen Marsh gas Nitrogen 

 Per cent Per cent Per cent Per cent 



Top .-21.6 78.4 



Middle 31.0 .... 33.3 35.6 



Bottom . . 37.1 58.0 4.9 



