DIPLOCOCCUS PNEUMONIA 97 



faint green color and grows best at 37 C. or 98 F., but 

 does not live long, requiring repeated transference to 

 fresh food. In sputum the pneumococcus may remain 

 alive and capable of producing disease for several 

 months if protected from light. If the sputum be 

 dried and powdered, so that it could be inhaled, the 

 cocci live for a few days in diffused light. Direct 

 sunlight kills them almost immediately. They are 

 killed at 52 C. or 126 F. in ten minutes. It is said 

 that the best way to disinfect sputum is by the addition 

 of about one-third alcohol. The pneumococcus itself 

 has a very low resistance to any of the ordinary 

 disinfectants, being killed in a few minutes. 



Most of the lower animals, particularly mice and 

 rabbits, but not birds, are susceptible to the pneumo- 

 coccus. But a true pneumonia as seen in man has 

 not been produced artificially. The pneumococcus 

 produces a small quantity of poison aside from itself, 

 but acts chiefly by reason of substances within the 

 germ cell. The resistance of animals to the pneumo- 

 coccus can be increased by repeated injections, but 

 the serum of such has no value in the treatment of 

 pneumonia. The use of vaccines has not been followed 

 by uniformly favorable results. The blood in pneu- 

 monia contains some agglutinins, but they are not of 

 much value in diagnosis. 



