20 DISEASES OF POULTRY. 



the houses are made air-tight with one or more layers of 

 building paper. There are various methods by which 

 such houses may be ventilated without endangering 

 the birds with currents of air, but as the details of these 

 methods depend largely upon the plan of building 

 adopted, they will not be discussed in this volume. 



Cleanliness is an essential sanitary condition for all 

 animals,. but particularly so for birds. Accumulations 

 of excrement harbor parasites, vitiate the atmosphere 

 and breed contagion. The poultry -house should, 

 therefore, be constructed with a view to its frequent, 

 easy, and thorough cleaning. The roosts and nest 

 boxes should be removable, so that all parasites which 

 collect upon them may be reached and destroyed. The 

 floor should be smooth to permit scraping and sweep- 

 ing. Cracks and knot holes should be avoided as they 

 furnish a hiding place for parasites. I^ow boxes con- 

 taining dry earth or road dust should be provided in 

 which the birds can take a dust bath with regularity. 



DISINFECTION. 



Disinfection is the destruction or removal of in- 

 fection. Infection of poultry -houses and runs occurs 

 from the introduction of animal and vegetable para- 

 sites, including the various microbes and unknown 

 forms of contagion. There are no precautions which 

 will entirely prevent such infection. The fowls with 

 which the flock is started will probably be already in - 

 f ected with many vari-^ties of parasites . Wild birds and 

 various animals or possibly the attandant may bring 

 contagion and even the larger animal parasites. Some 

 of these parasites multiply in the birds' bodies, others 

 breed in the houses, still others pass a portion of their 

 life cycle in or upon the soil of the runs. 



