The Bacteria of Consumption 87 



in the artificial cultures of the bacteriologist 

 (see Plate IX.). So we need not look to 

 sewage, polluted water, or dirty vegetables, 

 or rotting stuff of any kind as fruitful sources 

 of distribution. It is in tuberculous human 

 beings and tuberculous cattle that we find 

 the great sources of infection. 



Let us look first at the human source. The 

 masses of new tissue which form in the lungs 

 where tubercle bacilli grow are not well 

 supplied with blood, and so under the in- 

 fluence of the poisons which the bacilli set 

 free as they grow and flourish and die they 

 are apt to become friable and break down and 

 then little particles of them containing myriads 

 of living virulent germs are coughed up and 

 discharged in the sputum. So the sputum 

 of persons with tuberculosis of the lungs 

 and the secretions in their mouths and some- 

 times the nose and their lips often swarming 

 with bacilli are the immediate sources of 

 distribution of these sinister germs. 



Now, if the material which consumptive 

 persons cough up and spit out were always 

 destroyed at once by being burned or received 



