CHAPTER XXIII. 

 BACTERIA IN MANURES. 



The waste products of the animal body are elimi- 

 nated largely in the urine and feces. The latter consist, 

 in the main, of the undigested and indigestible parts of 

 the food; the urine contains the waste of all activities 

 of the different tissues of the body. The changes that 

 the food undergoes in the body of the animal, must be 

 looked upon as a part of the complex process by which 

 organic matter is again rendered available to the green 

 plant. The material that is eliminated from the animal 

 is much more easily decomposed by bacterical action than 

 is the food consumed. That which comes from the in- 

 testinal tract is already well advanced in the series of 

 changes that occur in the transformation of the organic 

 matter into stable form. It is interesting to know that the 

 work of the bacteria begins in the body of the animal, and 

 that their action on certain parts of the food is of value to 

 the animal, enabling it to make use of parts of the food 

 that without their aid would be impossible. 



As previously noted, the alimentary tract of animals 

 is to be considered as one of the natural homes of the 

 bacteria. Food is abundant, while temperature and 

 moisture conditions are favorable for rapid growth. 

 Over one-fourth of the solid matter in human feces con- 

 sists of bacterial cells. In the feces of the domestic ani- 

 mal, the proportion of bacteria is much less because of 

 the nature of the food. ^Millions of bacteria exist in 

 every gram of the manure. 



