212 FARMYARD MANURE 



of horses, cattle and other farm animals along with a 

 certain amount of, 



(3) litter used in bedding for the animals. 

 The dung in a fresh state contains from 70 to 80 per 

 cent, of water, and is composed of the insoluble and 

 undigested residue of the food with certain materials 

 derived from the digestive juices of the intestinal canal. 

 It is an exceedingly complex mixture, the chief substances 

 present in it being woody fibre, undigested cellulose, fat and 

 starch, mucus and bile pigments, together with certain de- 

 composition products such as indole and skatole produced 

 by putrefactive bacteria as well as fatty acids, alkaline 

 soaps, and small amounts of magnesium and calcium 

 phosphates. In the putrefactive and other fermentative 

 changes occurring in the intestines considerable quantities 

 of carbon dioxide, methane and hydrogen gases are 

 produced, and these are found in freshly voided dung 

 with free nitrogen derived from air which has been 

 swallowed with the food. 



The urine is a watery solution of chemical compounds 

 derived from the digested food and from waste products 

 arising in muscular and other tissues. It contains about 

 96 per cent, of water and 4 per cent, of dissolved 

 materials. The most important substance present in it 

 is urea^ a nitrogenous crystalline compound originating 

 from proteins absorbed by the blood, and in part ap- 

 parently from leucine and tyrosine produced by tryptic 

 digestion in the intestines. Urea is also a product of 

 the disintegration or wear and tear going on in various 

 organs. It amounts to about one half of the total solids 

 of the urine. Other nitrogenous waste materials are uric 

 and hippuric acids ; these are met with chiefly as sodium 

 salts, sodium and potassium hippurate being especially 



