On the toxic action of dilute pure sodium chloride solutions on the meningococcus

In experimenting during the past season with a large number of freshly isolated strains of the meningococcus, it was noticed that almost all of these were killed, when placed for a short time in dilute pure sodium chloride solutions. This action of sodium chloride is most toxic to the meningococcus when the concentration of the salt is not below 0∙85 per cent., and not much above 0∙9 per cent. NaCl. It was found that freshly isolated meningococci were more vulnerable to this action of NaCI, than old laboratory cultures. While old laboratory cultures could sometimes resist the action of a pure 0∙85 per cent. NaCI for three or four hours, freshly isolated strains seldom resisted its action for more than 20 minutes.