3IO MANUAL OF BACTERIOLOGY. 



ganism in the throats and nasal cavities of a number of domes- 

 tic pets and of persons not suffering from meningitis. 



A micrococcus about the size of the common pyogenic cocci; 

 grows in fours, but more often in pairs consisting of two hemis- 

 pheres separated by an interval which does not stain; usually 

 found within the pus-cells, in which respect it resembles the go- 

 nococcus. It is stained by ordinary methods with the aniline 

 dyes, and is decolorized by Gram's method. It does not grow at 

 the room temperature, but only in the incubator; gelatin is not 

 available as a culture-medium. There is no growth on potato 

 and scanty growth on agar or in bouillon. The development 

 is most abundant upon LofHer's blood-serum, when round, 

 white, shining, viscid-looking colonies with sharp outlines may 

 be seen in twenty-four hours. The serum is not liquefied. 

 Upon agar, or better upon glycerin- agar, the colonies are flat, 

 round, translucent, viscid-looking, having a yellowish-brown 

 color under the low power. The organism should be trans- 

 planted to fresh media frequently, as it rapidly loses its power of 

 reproduction. Many of the tubes inoculated with the original 

 material or with pure cultures show no growth. 



It is moderately pathogenic for guinea-pigs and rabbits 

 when inoculated into the pleura or peritoneum. Meningitis 

 and encephalitis have been produced in the dog and goat by 

 inoculation in the meninges. 



Flexner {loc. cit. pp. 141-167) found that injection of the 

 organisms into the spinal canal of monkeys produces a disease 

 the symptoms and lesions of which bear close resemblance to 

 those occurring in the natural infection in man. Injection 

 of monkeys into other parts of the body of monkeys produce 

 only local effects. 



This organism appears to be the principal if not the only 

 cause of epidemic cerebro-spinal meningitis. The lesion con- 

 sists of a purulent inflammation of the pia and arachnoid, ex- 

 tending into the brain-substance, over the cord and along the 



