228 FARMYARD MANURE 



nutrient solutions containing straw, paper or dead leaves 

 in " suspension " soon begin to evolve methane after 

 inoculation with a small amount of such mud. 



Henneberg and Stohmann found that from 50 to 70 per 

 cent, of the cellulose present in the hay, straw, and other 

 food consumed by horses and cattle disappears in its 

 passage through the alimentary canal of these animals 

 and is not recovered in the faeces. The extent of the 

 loss depends on the kind of cellulose, but even the 

 resistent forms met with in paper and wood shavings are 

 partially decomposed when taken into the bodies of farm 

 animals. It was at first assumed that these compounds 

 were digested by the enzymes of the stomach and 

 intestines, but the experiments of Tappeiner and others 

 have shown that the greater portion of the decomposition 

 is due to the action of cellulose- fermenting bacteria 

 existing in the first stomach of cattle and in the colon 

 and other parts of the large intestines of herbivorous 

 animals generally. The organisms break down the 

 cellulose into methane, hydrogen, and carbon dioxide, and 

 small amounts of other substances, which are used as 

 food or excreted in the urine and faeces. Tappeiner 

 showed that paper, straw, and other vegetable debris can 

 be fermented by material taken from the stomach and 

 intestines of cows and horses, the products obtained 

 being the gases just mentioned, and small quantities of 

 acetic and isobutyric acids. 



In manure heaps fermentation of the cellulose of the 

 litter and undigested residue of the food goes on and 

 the bulk of the organic material rapidly diminishes. In 

 the upper well-aerated parts of the heap complete oxida- 

 tion occurs, and carbon dioxide and water are the end- 

 products of the change ; but in the interior where 



