HOUSING AND HYOIENE 



263 



Such a condition is debilitating to the systena as well as 

 fatal to production. It is a law of universal application that 

 a debilitated condition always means weakened defensive 

 powers and a greater susceptibility to disease. 



Moisture is one of the essentials of the development of 

 disease germs in common with all other bacteria. The 

 more moisture there is in a building the more opportunity 

 there is for disease-bearing organisms to be present in large 

 numbers. 



Fig. 139 



A farm poultry-house having no ventilation. 

 Experiment Station.) 



(Courtesy of Purdue 



With the moisture of the body being constantly given off 

 by means of respiration and feces the air of the poultry-house 

 is bound to become laden unless it is as constantly replaced 

 with new air. 



Ventilation. — ^Ventilation is of profound importance, how- 

 ever, not only because of the relation to the elimination of 

 moisture. With the moisture of the expired air, gases are 

 also given off, the principal one of which is carbon dioxide. 

 Among these gases are certain ones that are actually poison- 

 ous if rebreathed. They are far more poisonous when 

 breathed by another individual than when breathed by the 

 individual giving them off. There is no reason to suppose 

 that the striking result reported by King,^ where a mouse 



' Physics of Agriculture. 



