642 NEISSERIA 



(see Eeport 1920) showed that, when freshly isolated, the living cocci were fatal 

 in smaller doses than the dead cocci, but after subculture for some time in the 

 laboratory, the lethal doses tended to approximate. Petrie (1937), who has made 

 a careful study of the endotoxin, finds that its effect on animals can be reproduced 

 by injections of other Gram- negative cocci, and that it belongs to a group of non- 

 specific, non-antigenic, thermostable, bacterial poisons. 



From these results, and from the fact that in animals dying from injection of 

 living cocci the blood and viscera are frequently sterile, it would appear that the 

 main cause of death is a toxaemia. Flexner (1907a) found that meningococci 

 undergo very rapid autolysis in culture ; as a result of this the endotoxins are 

 liberated from the bodies of the organisms, and it is these which are responsible 

 for the pathogenic effects in animals. This view is substantiated by the frequent 

 occurrence of haemorrhages on the serous membranes, of sterile transudates in the 

 cavities of the body, and of the adrenal haemorrhages which are found both in 

 animals and in human beings dying from the disease (Maclagan and Cooke 1917, 

 Petrie, 1937). 



The endotoxm can be extracted from the bodies of the menmgococci. One of the 

 simplest means (M. H. Gordon, see Report 1920) is to grind 005 gm. of dried cocci in an agate 

 mortar with 1-25 ml. of distilled water, to which after a few minutes 1-25 ml. of N/20 NaOH 

 are added ; the grinding is continued for about a minute. The cocci pass into solution 

 on the addition of the alkah. The M.L.D. of the fluid thus obtained is generally 01 to 015 

 ml. — that is, an amount corresponding to about 2 mgm. of the dried cocci (see also Petrie 

 1937). 



Though most workers have regarded the toxin of the meningococcus as essentially 

 an endotoxin there seems to be little doubt that under certain conditions it can 

 readily diffuse out into the medium. According to Ferry, Norton, and Steele (1931), 

 hormone broth cultures of pH 6-6 incubated for 4-6 days contain a filtrable toxin, 

 specific for each of the serological types of meningococci, as well as a group-specific 

 toxin common to all four types. Ferry and Schornack (1934) and Maegraith (1935) 

 have shown that these toxins, when inoculated by the intracisternal route 

 into guinea-pigs, give rise to convulsions and death within 24 hours. It would serve 

 no useful purpose to discuss how much of the toxic activity of these filtrates is due 

 to substances secreted by the living organisms and how much to substances liberated 

 from the dead organisms. There is evidence that the polysaccharide found in 

 Types I and III is soluble in suitable media (Petrie 1932, Kirkbride and Cohen 1934), 

 and it may be that the nucleoprotein to which Boor and Miller (1934) ascribe the 

 toxicity of the meningococci is likewise soluble to a greater or less degree. The 

 main conclusion is that for laboratory animals dead cocci are almost as fatal as Uving 

 cocci, and that the tissue reactions are determined by toxic substances liberated 

 from the organisms either before or after their death. (For a review of the meningo- 

 coccus see Branham 1940). 



Neisseria meuiugitidis 



Synonyms. — -Meningococcus ; Diplococcus intracellularis meningitidis of Weichselbaum. 

 Isolation. — From cerebrospinal fluid of patients with meningitis by Weichselbaum in 



1887. 

 Habitat. — Strict parasite ; found in nasopharynx of man. 



