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cilli are present, will not always destroy them. Common 

 salt liberally applied to meats is fatal to the germ in one 

 month; but in large masses of meat, the salt may not per- 

 meate the mass evenly and many bacilli may thus escape the 

 destructive action of the salt. 



In truth, there are probably many conditions outside of 

 the animal body in which the tubercle bacillus may live and 

 retain its virulency that are yet unknown to pathologists. 

 However, it is certain that poorly ventilated and dark living 

 rooms, public halls, school rooms and churches are places 

 where the infected sputa may be slowly dried, thus pre- 

 serving its infective power indefinitely. Hence, the dust 

 from such rooms may carry the virulent germs into the air 

 passages, and into the alimentary canal with the food. 

 In fact the greatest number of cases of tuberculosis in the 

 human family are contracted by breathing tuberculous dust 

 in living rooms, churches, school rooms and public places. 

 The next greatest number of cases of tuberculosis are con- 

 tracted by eating tuberculous food. 



ACCESSORY OR PREDISPOSING CAUSES OF TUBERCULOSIS. 



Predisposing causes consist of influences or factors that 

 reduce the animal vigor and the resisting power of the leu- 

 cocytes and tissues of the animal body, and of conditions 

 which favor the introduction of the germs into the body. 



(1). Heredity produces a tendency in the cell structure 

 of the body favorable to the development of the germ and 

 depressing more or less the body vitality or vigor. The 

 offspring of tuberculous parents readily contracts tubercu- 

 losis, because the protecting liquids and cells of the body 

 can not prevent the invasion of the tubercle bacilli. In rare 

 instances the bacilli pass into the embryo or unborn foetus. 

 Some authorities claim that the germ may pass from a tu- 

 berculous sire in the semen, or it may be in the ovum from 

 the dam, or pass from the mother to the foetus by way of 

 the foetal membranes. 



Evidently the continued breeding of tuberculous animals 



