The Cause and Prevention of Tuberculosis 321 



500. The Chief Mode of communicating Consumption. 



The chief mode of communicating consumption is by the 

 dried sputum of consumptives. The germs of this disease 

 exist by the million in the sputum which may be hawked or 

 coughed up and cast upon the sidewalk, the floors of public 

 halls, schoolrooms, workshops, and public buildings, or upon 





FIG. 172. Louis Pasteur (1822-1895). 



(This picture represents Pasteur, the great master of modern science, 

 busily at work in his laboratory recording the results of his study 

 of bacteria.) 



the floors or carpets in dwelling houses. In fact, any place 

 where the consumptive may choose to spit may become 

 infected. 



When the sputum becomes dried, the germs which it con- 

 tains in countless numbers mingle with the air and dust. It 

 may thus infect susceptible persons and spread the disease to 

 many. The danger of infection is increased by the great 

 vitality of the germs, which exist for a long time after drying 

 and mixing with the dust. 



