COCCUS OF MENINGITIS 149 



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-pneumococci 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 stimu- 

 lates phagocytosis. It has been used therapeutically in man for 

 the cure of pneumonia with hopeful results. Oleate of soda aids 

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

 varieties of immune sera (see page 76). Most mammals, but few 

 if any birds are susceptible to the pneumococci; mice, being 

 very easily infected, are used for isolation purposes. 



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. 



Pneumococcus mucosus, also called Type III is distinguished 

 by its large size, long chains, capsule, more generous growth 

 in large moist colonies of not such a distinct green color and its 

 ability to produce a serious form of pneumonia. 



COCCUS OF MENINGITIS 



Micrococcus Meningitidis. 



Diplococcus intracellularis meningitidis. 



Meningococcus (Fig. 38). 



This organism is the cause of epidemic cerebro-spinal meningitis. 



Morphology and Stains. Resembles the gonococcus closely, 



