AND PREVENTION OF PHTHISIS. 411 



father and daughter were dead, the daughter having 

 been the first to succumb. 



In opposition to those who consider that they have 

 found bacilli in the breath of phthisical patients, Cornet 

 adduces a number of very definite results. Patients 

 have, been caused to breathe against plates of glass 

 coated with glycerine, which would undoubtedly have 

 held the bacilli fast. Water has been examined, through 

 which the air expired by phthisical lungs had been 

 caused to pass. In this case the bacilli, being moist, 

 would have been infallibly intercepted by the water. 

 The aqueous vapour exhaled by consumptive lungs has 

 been carefully condensed by ice ; but no bacilli has, in 

 any of these cases, been detected. It behoves those 

 who have arrived at an opposite result to repeat their 

 experiments with the most scrupulous care, so that no 

 doubt should be suffered to rest upon a point of such 

 supreme importance. The lungs, air-passages, throat, 

 and mouth all present wet surfaces, and it has been 

 proved that even with sputum rich in bacilli, over 

 which a current of air of considerable force had been 

 driven, the air was found perfectly free from the 

 organism. 



The immunity as regards infection which to so 

 great an extent is observed, is ascribed by Cornet in 

 part to the intensely viscous character of the sputum 

 when wet. Even after it has been subjected to a dry- 

 ing process its complete desiccation is opposed by its 

 hygroscopic character. Cornet calls other investigators 

 to bear him witness that the task of reducing well-dried 

 sputum to a fine powder, even in a mortar, is by no 

 means an easy one. It is difficult to produce, in this 

 way, a dust fine enough to remain suspended in the air. 

 It would be an error to suppose that dry tuberculous 

 phlegm, when trodden upon in the streets, sends a cloud 

 27 



