Respiration 



177 



266. The Danger from Pulmonary Infection. The germ 

 of pulmonary consumption, known as the bacillus tuberculosis, 

 is contained in the breath and the sputa from the lungs 

 of its victims. It is not difficult to understand how these 

 bacilli may be conveyed through the air from the lungs of 

 the sick to those of apparently healthy people. Such per- 

 sons may, however, 

 be predisposed, 

 either constitution- 

 ally or by defective 

 hygienic surround- 

 ings, to fall victims 

 to this dread disease. 

 Overcrowding, poor 

 ventilation, and 

 dampness all tend to 

 increase the risk of 

 pulmonary infection. 



These bacilli are 

 not necessarily 

 transmitted directly 

 through the air from 

 the lungs of the sick 

 to be implanted in 

 the lungs of the 

 healthy. They may 

 remain for a time in -the dust of damp, filthy, and over- 

 crowded houses. The dust contains the germs, and thus 

 they may enter the body with the air breathed. In a 

 congenial soil the bacilli retain their vitality for a long 

 time, and possibly may take on more virulent infective 

 properties than they possessed when expelled from the 

 diseased lungs. 



FIG. 92. Bacillus Tuberculosis. 



(A minute portion of sputum from a case of phthisis, 

 or " consumption " of the lungs, magnified by 

 1000 diameters. These bacilli are rod-shaped 

 bacteria, stained to show black. The black spots 

 in the figure are merely the debris in the spu- 

 tum, also stained to show black.) 



