The Role of the Phagocyte in Cerebrospinal Meningitis. 425 



growing the meningococcus. It varies also with the character of the strain 

 of meningococcus employed, as some grow very rapidly on artificial media, 

 while others grow slowly. 



The following Table gives roughly the number of germs of Strain " P," 

 which, having been planted out in similar definite quantities on the following 

 media, gave growth after incubation at 37° C, for 48 hours : — 



]Vame of medium. 



Growth positive. 



Growth negative. 



War Office legumen trvp-agar 



Amino-acid agar, mixed with fresh blood 



Blood agar 



50,000,000 germs 



10,000,000 germs 



10,000,000 germs 

 10,000,000 „ 

 10,000,000 „ 



1,000 „ 



10,000,000 germs. 



100,000,000 „ 

 1,000,000 



100,000,000 „ 

 1,000,000 „ 

 1,000,000 „ 

 1,000,000 „ 



100,000,000 „ 





In the above Table a thousand germs was the smallest number planted out. 

 Chocolate medium will, however, readily grow the meningococcus in 

 inoculations of 500 cocci. In implantations made from glucose broth 

 cultures, this number is reduced still lower, as presumably, in this instance, 

 all the cocci are alive. Experiment has shown that growth will then take 

 place, on this medium, in implantations of as few as 20 or 30 organisms. 



"We drew the conclusion from the above facts (1) that chocolate medium 

 was well adapted to our requirements, and was suitable for testing the 

 viability of the meningococcus, as far as this can be determined on artificial 

 media ; (2) that, given a reasonable number of germs to an implantation, 

 failure to grow on our medium denoted the presence of almost a negligible 

 number of cocci. 



One of us has shown that nearly all strains of the meningococcus succumb 

 rapidly in the presence of - 85 per cent. NaCl solution, on exposure to its action 

 for a short while.* All the strains of the meningococcus used in the following 

 experiments were found to be highly susceptible to the toxic action of dilute 

 NaCl. While a - 85 per cent. NaCl solution is toxic, a 1*5 per cent. NaCl 

 solution is more or less harmless. In the following experiments, taking fresh 

 spinal fluid obtained from lumbar puncture of cerebro-spinal fever patients, 

 and lightly centrifuging down the leucocytes, we have made use of this toxic 

 action of a - 85 per cent. NaCl solution to kill all the meningococci outside 

 or attached to the leucocytes, while those enclosed within them are protected 

 from its action. 



* Shearer, " On the Toxic Action of Dilute Pure Sodium Chloride Solutions on the 

 Meningococcus," ' Roy. Soc. Proc.,' B, vol. 89, p. 440 (1916). 



