HYGIENE AND SANITATION 163 



The organic impurities are animal and vegetable substances. 

 Water will be so contaminated if it comes in contact with 

 animal excreta or animal refuse of any kind, including dead 

 animals and bowel discharges. 



In percolating through the soil the earth acts as a filter and 

 there is a tendency to purify polluted water There is a con- 

 stant oxidation, by aid of germs, of all kinds of organic matter 

 on and in the soil. 



Water from cultivated lands is usually very impure on 

 account of the large amount of organic matter gathered from 

 it. 



Certain diseases are said to be water-born, that is, the germs 

 causing the disease gain entrance into the water, and fowls 

 drinking the polluted water may become inoculated and con- 

 tract the disease. A bird may die of cholera and be thrown 

 into the stream or close to the stream, so that seepage in time 

 of rain may carry the contagium into the water and thus form 

 a source of danger; or drainage from a yard containing in- 

 fected droppings from birds with cholera or other contagious 

 bowel diseases may find its way into the stream, and this 

 contaminated water may pass for miles down country and other 

 fowls consuming the germ-laden water may contract the 

 disease. 



As a rule, it is considered that germs of disease do not live 

 indefinitely in the water, but after a while die. 



Puddles of polluted water in the barynard or hen yard may 

 contain embryo of intestinal worms or harmful germs. Moist 

 places are favorable locations for the preservation of the em- 

 bryonic worm outside the body, awaiting a time to be taken 

 up by a susceptible bird. 



AIR 



Pure air is of the utmost importance to successful incuba- 

 tion brooding, and to any class or age of birds. While the 

 bird may do without water and food for hours, or even a day, it 

 must have a constant supply of fresh air. Polluted air soon 

 makes an alarming change in the organism. Since the living 

 processes are going on in the animal body every minute, and 

 even every second, it must be remembered that this means a 



