THE MENINGOCOCCUS 297 



various papers in the Lancet and Brit. Med. Journ. for 1915 

 1920. 



Clinical Examination 



1. In a case of suspected cerebro- spinal fever, no time should 

 be lost in obtaining aseptically some cerebro -spinal fluid by 

 lumbar puncture. The fluid should be examined as soon as 

 possible and should be kept warm in the incubator, in the pocket, 

 or in a thermos flask with warm water, until finished with. 



a. The fluid will probably be thickly turbid. Smears should 

 be made with the deposit, obtained by allowing the fluid to stand 

 for a little while or by centrifuging lightly. Some of the smears 

 may be stained with Leishman (see " Malaria ") or with Loffier's 

 or thionine blue, others by Gram's method, counter-staining with 

 Bismarck brown. The presence of diplococci and groups of diplo- 

 cocci which are Gram-negative within the polymorphonuclear 

 leucocytes, which form the majority of the cells in the fluid, 

 is practically diagnostic (the gonococcus may cause a cerebro - 

 spinal meningitis, but this condition is so rare that it may be 

 neglected). A few cocci and diplococci may be free in the fluid. 

 At an early stage and in some of the fulminating cases the fluid 

 may be nearly free from cells and the meningococcus difficult to 

 detect microscopically. It can, however, generally be found after 

 centrifuging and by careful examination. 



If the cocci are not found microscopically, they may some- 

 times be demonstrated after incubating the fluid at 37 C. for 

 twenty-four hours. 



At a late stage in the disease, the cocci may disappear from the 

 cerebro -spinal fluid and the polymorphs be largely replaced by 

 lymphocytes. 



b. Cultures should be made by smearing some of the fluid on 

 to plates of blood-, serum-, or legumin- agar, preferably the two 

 former, and incubating at 37 C. The plates are examined after 

 twenty-four and forty -eight hours' incubation, suspicious colonies 

 being examined microscopically with Gram -staining, and sab- 

 cultured on to blood agar, etc., some tubes being incubated at 

 37 C., others at 23 C., and into litmus glucose and litmus 

 saccharose serum broth (also mannose, if available). Cultures 

 are best made both before and after incubation of the fluid ; the 

 latter sometimes succeed when the former have failed. Hope of 



