Tuberculosis. 113 



surprise that I had taken every representative of a given family, 

 and left the pure bred members of the second family untouched. 

 Both families had mingled freely in the pastures and yards, yet 

 the second family furnished no tuberculous cases and remained 

 sound from that time onward. 



b. Close Buildings, Lack of Ventilation. 



Air rendered impure by repeated breathing is so favorable to 

 the propagation of tuberculosis that it has been looked upon as 

 the sole cause (Macormac). Though now certain that this can- 

 not produce tuberculosis at all in the absence of the germ, yet it 

 is such a potent accessory cause when the bacillus also is present, 

 that its importance cannot be too highly appreciated. 



For the mild cases of tuberculosis in man life in the open air, 

 day and night, in a genial climate with pure air affords one of the 

 best grounds of hope of recovery or mitigation. In the Burden 

 herd above referred to, animals condemned in the spring spent 

 the summer at pasture, with a general appearance of perfect 

 health, yet, when returned to the barns in the fall, they fell off 

 so that soon some of them had to be helped to rise in the stall. 

 All the world over city dairy cows are notorious for tuberculosis. 

 In Europe where the country cattle are affected in a ratio of i to 2 

 per cent., those in the city dairies suffer to the extent of 6 to 20 

 per cent, and upward. Of our plains and prairie steers the gov- 

 ernment inspectors, at the abattoirs, condemned as tuberculous 

 but 0.02 per cent., whereas of the city dairy cows, mostly recently 

 from the country, they condemned 1.23 per cent. The ratio is 

 I steer to 60 cows, a most striking showing in favor of an open 

 air life. 



c. Dark Stables. 



Dark stables are usually dirty and ill-ventilated, and as such, 

 lower the general health of the inmates and strongly predispose 

 them to tuberculosis. The darkness, however, acts indirectly in 

 depriving the tissues of the body of their due supply of air. The 

 formation of green pigment (chlorophyll) in plants, and that of 

 red pigment in the blood globules are alike due to the action of 

 light. In darkness both disappear. But the red globules of the 

 blood are the bearers of oxygen to all parts of the body, and if 

 these globules are deficient the whole body is denied its due 



