132 BACTERIOLOGICAL DIAGNOSIS. 
upon the nature of the organism which is probably 
present; for general purposes stain one or more films 
with Léffler’s methylene blue (two minutes), wash, dry, 
mount, and examine. 
Streptococci and staphylococci will be readily re- 
cognised by their morphological characters. Ifdiplococci 
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 intracellularis 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- 
