132 BACTERIOLOGICAL DIAGNOSIS. 



upon the nature of the organism which is probably 

 present ; for general purposes stain one or more films 

 with LofHer's methylene blue (two minutes), wash, dry, 

 mount, and examine. 



Streptococci and staphylococci will be readily re- 

 cognised by their morphological characters. If diplococci 

 are present they may be pneumococci, Weichselbaum's 

 diplococci, or gonococci. Stain a film by Gram's 

 method and counterstain in dilute carbol-fuchsin in the 

 method described for the gonococcus. Pneumococci 

 will retain the violet stain, while Weichselbaum's 

 organism and gonococci will be coloured red. 



Weichselbaum's diplococcus meningitidis intmcellularis is 

 now generally considered to be the specific cause of 

 cerebro-spinal fever. It is a medium-sized diplococcus, 

 the components of the pairs being approximately hemi- 

 spherical in shape and having their flat surfaces turned 

 towards one another. This organism has a strong 

 resemblance to the gonococcus, and this likeness is 

 increased by the facts that it is decolorised by Gram's 

 method and that it is mostly contained within the 

 polynuclear leucocytes of the inflammatory exudation. 

 The two differ in their cultural characters and in their 

 pathogenicity to animals. If any question should arise 

 as to which of the two is present in the meningeal 

 exudation in a case in which no cultures have been 

 taken, some help may be afforded by the fact that the 

 diplococcus meningitidis often occurs in the nasal secretion 

 in cerebro-spinal fever. It is scarcely necessary to say 

 that other evidence of gonorrhceal infection should be 

 sought for. 



Still's diplococcus of posterior basic meningitis can- 

 not be distinguished from the diplococcus meningitidis 

 by its morphological characters alone, and many bac- 



