206 INFECTION AND IMMUNITY 



and vital resisting power of the individual attacked. 

 Depressing influences of all kinds predispose to an 

 attack, and especially alcoholism, malnutrition, and 

 insanitary surroundings. Pneumonia also frequently 

 occurs as a complication of other infectious diseases- 

 measles, influenza, typhoid fever. 



It is most prevalent during the spring months. In 



FIG. 9. Micrococcus of pneumonia; magnified 1000 diameters. A, with 

 " capsule," as seen in the blood of an infected animal ; B, as seen in a culture 

 fluid. 



the United States the area of greatest prevalence is the 

 Middle Atlantic Coast region. The Gulf Coast region 

 and the South Atlantic Coast region have the smallest 

 proportion of deaths from this disease. The North At- 

 lantic Coast region, the Interior Plateau, the Central 

 Appalachian region and the region of the Great North- 

 ern Lakes have all about the same rate (103 to 106 



