THE MENINGOCOCCUS GROUP 331 
media to such a decree that transfers made at less frequent intervals 
suffice to maintain the viability of the culture. 
The meningococcus exliibits little resistance to heat, drying or the 
action of chemical agents. Five minutes' exposure to 65° C. or two 
minutes' exposure at S()° C. suffices to sterilize the culture. Drying 
for a few hours at 30° C. is likewise fatal to the organism. Exposure 
of the organism to carbolic acid broth (1 to SOO) inhibits develop- 
ment, and drying in the dark for seventy-two hours is fatal; sixty 
hours' exposure to drying at 37° C. is insufficient to kill the organisms.^ 
Products of Growth.— Meningococci are culturally very inert. No 
proteolytic enzymes have been demonstrated; gelatin and blood serum 
are not liquefied, and no coagulation or peptonization of milk occurs. 
Indol, skatol, phenol or other products of similar nature are not 
demonstrable in cultures of the organism. Acid, but no gas, is pro- 
duced with considerable regularity in glucose and maltose broths;' 
Fig. 45. — Meningococci from cerebrospinal fluid. X 1200. (Kolle and Hetsch.) 
other ordinary carbohydrates are unattacked. These fermentation 
reactions are of considerable value in the cultural difi'erentiation of 
meningococci from other organisms which may readily be confused 
with them. 
Toa-in^.— Soluble exotoxins have never been demonstrated among 
the products produced by the meningococcus; killed cultures of the 
organism appear to be as fatal for ordinary experimental animals as 
the living organisms. This would suggest that the toxic phenomenon 
may be attributable to the liberation of endotoxins rather than to a 
soluble toxin. Flexner^ has produced direct evidence that the pro- 
ducts of dissolution of the meningococcus are the direct cause of the 
' Councilman, Mallory and Wright: Loc. cit., p. 78. 
2 Kopetsky (Meningitis, The Laryngoscope, 1912, 22, 797) has called attention to 
the early disappearance of the reducible substance (glucose) normally present in the 
spinal fluid in cerebrospinal meningitis. It is i)Ossible that the action of the organism 
upon this substance explains the phenomenon. 
3 Jour. Exp. Med., 1907, 9, 142. 
