132 BACTERIA 



abstracted from veins is mixed with 500 c.c. of milk and incubated. 

 In twenty-four hours pneumococci, if present, grow luxuriantly. 

 Just before the crisis the organisms will not grow. 



Immunity and Susceptibility. The susceptibility of man varies 

 greatly. Exposure to cold and hardships of various kinds predis- 

 pose to pneumonia. One attack does not prevent another. It has 

 been observed that normal leucocytes only become phagocytic 

 toward the pneumococcus when lying in anti-pneumococcic serum. 

 It has even been noticed that these organisms grow better in 

 the anti-serum, rather than in the normal serum. Animals have 

 been immunized by injecting cultures and toxin. The immune 

 serum thus produced protects small animals against infection, and 

 stimulates phagocytosis. It has been used therapeutically in man 

 for the cure of pneumonia with doubtful results. Oleate of soda 

 aids in bacteriolysis of pneumococci by sera, if added to the 

 various varieties of immune sera. 



Agglutination of pneumococci is caused by the blood of infected 

 individuals, even diluted at 1-60. Immune serum also has the 

 same action. 



Opsonins increase during the course of pneumonia and are at 

 their height at or just after crisis. 



Two intermediary streptococci are Str . viridans and Str. fnucosus, 

 Sir. viridans is like the Str. pyogenes but produces germ colonies. 

 It is most frequently met as the cause of valvular endocarditis. 

 Str. mucosus is a long chain former surrounded by a halo not stain- 

 able as a capsule and produces viscid exudate. In some ways it 

 resembles the pneumococcus. 



The various streptococci from pus, saliva, feces, manure and sew- 

 age are differentiated by their action on blood, milk and the sugars. 





 COCCUS OF MENINGITIS. 



Streptococcus Intracellularis. 



Diplococcus intracellularis meningitidis. 

 Meningococcus. (Fig. 40.) 



