n6 The Story of the Bacteria 



into the blood, so that there is what we have 

 learned to call a bacteriaemia as well as an 

 inflammation of the lungs. In the lungs a 

 great many leucocytes as well as other ma- 

 terial accumulates in the air spaces and this 

 sometimes makes the patient short of breath. 

 The pneumococcus is a 

 very minute lance-shaped or- 

 ganism, which is often sur- 

 rounded by a transparent 



FIG. 12. THE PNEU- J 



MOCOCCUS capsule (Fig. 12). It can be 



This shows the artificially cultivated, but 



delicate transparent it is a very sensitive and 



capsule which sur- s hort-lived thing, easily killed 



rounds the bacteria. J 



by drying, by sunlight, and 

 ordinary disinfectants such as carbolic acid. 

 It is present in the mouth and nose of a 

 considerable proportion of healthy persons 

 to whom it ordinarily does no harm. Just 

 what the conditions are which set this germ 

 at work in the lungs, we do not know very 

 definitely. Old people and infants are par- 

 ticularly susceptible. Feeble, overworked, ill- 

 nourished, debilitated folks, and those who 

 stay in very dusty places are also liable to 



