Leahy. — The Fight against Tuberculosis. 221 



instance, the lungs — and find the locality favourable for its 

 growth, it begins to multiply, damaging the tissues badly 

 during the process, and the condition known as tuberculosis 

 of the lungs becomes established. The point to be em- 

 phasized here is that every form of tuberculosis is caused by 

 the tubercle bacillus, and by it only, and therefore the eradi- 

 cation of tuberculosis means the eradication of the tubercle 

 bacillus. 



Under ordinary circumstances tubercle bacilli are ex- 

 tremely tenacious of life, though with suitable means they 

 may be easily killed. The sputum of consumptives teems 

 with these organisms, and is the most prolific means of 

 spreading infection. So that clearly this is a question requir- 

 ing serious consideration. 



We have all observed the absence of dust inside our homes 

 as well as out-of-doors in damp weather, the reason being, 

 of course, that the moisture in the atmosphere condenses on 

 the particles of dust in a room, overweights them, and they 

 sink down and settle on the floor or walls, the air so be- 

 coming clarified. I mention this every-day fact to make 

 clearer a point I wish to bring out — namely, that it is not the 

 sputum or spittle just when dejected from a patient in a 

 moist condition and so containing the bacilli in certain con- 

 fined limits that is the trouble, but the danger arises when 

 the sputum dries up, becomes pulverised, and floats about in 

 the atmosphere, to be breathed in by all and sundry. 



We do not all get tuberculosis, though frequently exposed 

 to risks, any more than we get many other diseases ; that, 

 however, is another question, introducing the subject of im- 

 munity, which it is not within the scope of this paper to 

 discuss. Suffice it, then, to summarise thus : — 



(a.) Tuberculosis in every form is due to the tubercle 

 bacillus. 



(b.) The most fertile, if not the only, source of human 

 tuberculosis is the sputum of consumptives allowed to dry 

 and get converted into dust, so contaminating the air. 



(c.) Tuberculosis is infectious. 



(d.) Tuberculosis is preventible. 



Tuberculosis is, then, an infectious disease, and any per- 

 son, place, or thing contaminated by the expectoration of 

 consumptives is a focus of infection for human beings. Hence 

 houses or rooms inhabited by consumptives are infectious, as 

 has been sufficiently proved many times ; also handkerchiefs, 

 &c, used by such persons are obviously infectious, and the 

 filthy habit of indiscriminate spitting is a prolific source of 

 infection. 



I think the above is sufficient explanation of the main 

 factors in the spread of tuberculosis so far as is relevant to 



