AIE 



51 



animals which have been affected with the disease. The 

 spores are disseminated through the air of the factory with 

 the dust, and internal anthrax results. By sorting wool 

 after damping it the spores and dust no longer arise and 

 infection is controlled. 



Pleuro-pneumonia is undoubtedly an air-borne disease, 

 and one explanation of the rapid spread of cattle plague is 

 through air infection. 



A form of pneumonia in the horse which certainly looks 

 infectious is very common on board a ship; it is nearly 

 always fatal, runs a very rapid course, and if it is not 

 attributable to a distinct microbe, then the foul air of the 

 horse-decks must be held responsible. 



Infectious pneumonia of horses on land is also described, 

 which if it exists must be air-borne. Certainly the poison 

 of influenza is carried in this way, and this disease is 

 frequently associated with pneumonia. 



The spread of tuberculosis in crowded cow-sheds is well 

 recognised ; it is not difficult to believe that many of these 

 cases must be by air infection. 



In the present state of our knowledge we hesitate to 

 include that very fatal disease of calves, ' white scour,' as 

 due to air poisoning, for there is evidence that infection 

 may be principally by the digestive tract. One important 

 practical point clearly stands out : if the cows calve in the 

 open and away from the filthy surroundings of their houses, 

 cases no longer occur. There may be quite another expla- 

 nation of the observed result than on the theory of pure air, 

 but the fact remains. 



It is hopeless to attempt to treat chest cases in a badly 

 ventilated stable ; fresh air has never yet killed man or 

 animal, it is the wind that kills. 



Pneumonia may with advantage be treated in the 

 open if there is nothing to choose between that and a 

 badly ventilated place, and the same remark applies to 

 all medical and surgical cases. In the human subject 

 the open-air treatment of tuberculosis has been fully 



accepted. 



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