EPIDEMIC CEREBROSPINAL MENINGITIS 245 



can be seen in the heart blood to possess capsules. It is less pathogenic 

 to rabbits and dogs, but when injected into the trachea in these animals 

 it originates a pneumonia. As stated above, it is the only organism 

 present in a small number of cases of human pneumonia, and it has also 

 been isolated from conditions of empyema, meningitis, appendicitis, and 

 pyaemia ; a bacillus closely related or identical has been found in rhino- 

 scleroma (?•«.). It is a not infrequent inhabitant of the mouth and nose 

 of healthy individuals. From its historical associations an altogether 

 undue importance has been attached to this bacillus. 



In septic pneumonias the ordinary pyogenic bacteria, alone 

 or associated with the pneumococcus, are found. 



V 





Epidemic} Cerebro-Spinal Meningitis or Cerebro- 

 spinal Fever. 



As the result of observations on this disease in different parts 

 of the world, it has been now established that the causal agent 

 is the diplococcus intra- 

 cellular is meningitii lis, 

 first described by Weich- 

 selbaum, and now usually 

 known as the meningo- 

 coccus. This organism is 

 a small coccus measuring 

 about 1 /* in diameter ; 

 it usually occurs in pairs, 

 the adjacent sides be- 

 ing somewhat flattened 

 against each other. In 

 most cases the cocci are 

 chiefly contained within 

 polymorphonuclear leuco- 

 cytes in the exudation 

 (Fig. 65); in some cases, 

 however, the majority 

 may be lying free. It 

 stains readily with basic 

 aniline dyes, but loses 



the stain in Gram's method. Both in appearance and in its 

 staining reactions it is closely similar to the gonococcus (vide 

 p. 255). The organism can readily be cultivated outside the 

 body, but the conditions of growth are somewhat restricted— 

 "trypagar" (p. 43), agar with an admixture of serum, ascitic 

 fluid, or blood (p. 45) is to be recommended. The optimum 

 reaction is [one neutral to phenol- phthalein. Growth takes place 



/ 



Fig 



.. . 65. — Film preparation of exudation from 

 a case of meningitis, showing the meningo- 

 cocci within leucocytes. See also Plate I., 

 Fig. 3. 

 Stained with carbol-thionin-blue. x 1000. 



