GROUP OF PYOGENIC COCCI. 
55 
meningococcus or the Micrococcus intracellular is men¬ 
ingitidis, and must not be confused with the forms 
mentioned above, which are always secondary. 
The meningococcus was identified and described 
by Professor Weichselbaum in 1887. The micro¬ 
organism was found in the cerebrospinal fluid of pa¬ 
tients sick with the disease, and generally within the 
bodies of the leucocytes. For this reason the term in¬ 
tracellular is used in its description. The coccus occurs 
in pairs, a diplococcus which in appearance is not un¬ 
like the gonococcus. It is Gram negative. It can be 
cultivated on agar containing blood or ascitic or hydro¬ 
cele fluid. Three types of the meningococcus are 
recognized, the meningococcus and the parameningo¬ 
coccus, A and B. 
The presence of the disease is detected by finding 
the meningococcus in the cerebrospinal fluid, which is 
withdrawn by inserting an aspirating needle into the 
cerebrospinal canal, at the level of the third or fourth 
lumbar vertebra. This procedure is spoken of as lum¬ 
bar puncture, and may be performed by physicians 
without danger to the patient. The fluid recovered in 
this manner is usually cloudy and is immediately cen¬ 
trifuged to throw down the cellular elements contained 
in it. After this has been done the deposit is spread 
thinly on slides, stained by Gram’s method, and ex¬ 
amined under the microscope. The meningococcus 
when present is identified by its shape and arrangement 
in pairs, and by its location within the bodies of the 
leucocytes, The micro-organism may be cultivated 
Morphol¬ 
ogy 
