58 BACTERIA IN DAILY LIFE 



specially affects the air passages ! What applies 

 to speaking applies to a still greater degree to the 

 act of coughing or sneezing. 



To Schaffer we owe the discovery that leprosy 

 bacilli may be disseminated in immense numbers 

 by the coughing of leprosy patients, whilst it has 

 been estimated that a tuberculous invalid may 

 discharge a billion tubercle bacilli in the space of 

 twenty -four hours, whilst the dried sputum of 

 consumptive persons has actually engendered 

 tuberculous symptoms in the lungs of animals 

 which were made to inhale it. Plague bacilli have 

 been found in masses in the mouths of plague 

 patients, and were found, moreover, before any 

 symptoms of the disease had declared themselves ; 

 and the sputum of infected persons is regarded by 

 some authorities as one of the most important 

 vehicles by which plague is spread. The culp- 

 ability of air in the dissemination of tuberculosis 

 amongst animals has been made the subject of 

 some very exhaustive and valuable investigations 

 by Kasselmann. In as many as 71 per cent, of 

 bovine tuberculosis cases the respiratory organs, 

 Kasselmann found, were the seat of the disease. 

 The undoubted contamination of the air which 

 takes place in the surroundings of tuberculous 

 animals is not, however, due to the bacilli being 

 exhaled by such cattle in the mere process of 



