DAIRY INSPECTION 



147 



effect of sunlight is not fully appreciated. Experiments 

 with artificial cultures of various bacteria have shown 

 that direct sunlight is very destructive to germ life, while 

 the action of diffused light, although less powerful, is also 

 quite effective. Tubercle bacilli are killed by direct sun- 

 light in a few hours, while even diffused daylight destroys 

 them in a few days (Koch) . 

 Direct sunlight kills anthrax 

 spores in five hours and the 

 bacilli in thirty hours, spores 

 being more susceptible to 

 sunlight than bacilli (Ar- 

 loing, Roux). Direct sun- 

 light destroys or decreases 

 the virulence of colon bacilli, 

 the bacilli of fowl cholera 

 and swine erysipelas, and the 

 virus of hog cholera, while 

 diffuse daylight also exerts 

 a similar but less powerful 

 action (Neumark). 



The inspector should 

 note the location and size of 

 the windows and determine 

 the total square feet of win- 

 dow surface. He should Flo 12 _ windowarrangedtoactasafresh 

 also observe whether the air inlet (Wis ' E * p ' Sta ' BulL No ' 266) ' 

 glass is clean and if other buildings obstruct the en- 

 trance of light. Three to four square feet of win- 

 dow surface for each cow will usually admit sufficient 

 light, provided the windows are properly placed and 

 equally distributed. In cold climates, an excess of win- 

 dow surface may increase the radiation of heat to such an 



