MENINGOCOCCUS 59 



In addition to the genital organs, the gonococcus may at times invade and be 

 isolated from the eye (gonorrhoeal ophthalmia), the joints, rarely as a cause of 

 endocarditis and possibly as the factor in septicaemia. Grown upon hydrocele or 

 ascites agar, or blood-streaked agar, or upon blood agar from man or the rabbit, 

 the colonies appear as irregular, minute, dew-drop spots. By the second or third 

 day the involution forms are abundant, and within four to seven days the culture 

 will probably be found to be dead. Unless frequent transfers are made, it will be 

 best kept alive on blood agar. The organism grows best at 37 C., and will not 

 grow below 25 C. It will not grow on plain or glycerine agar or ordinary blood- 

 serum unless the transfer of considerable pus in inoculating the slants gives it a 

 suitable culture medium. In material from joints, it is in the fibrin flakes that the 

 gonococci are most .apt to be found, if found at all. 



By heating the blood-streaked agar tubes to 56 C. for twenty minutes (in- 

 activation-destroying complement and hence bactericidal power of blood on slant) 

 greater success in primary cultures will be obtained. 



In culturing gonococci the transfer of material to culture media 

 should be made with the least delay possible. 



The most satisfactory medium is Thalman's medium upon the 

 slanting surface of which we have deposited two or three drops of 

 human serum. Blood may be taken from a vein or the Wright U tube 

 may be used and after centrifuging the sterile serum is taken off with 

 a capillary bulb pipette and deposited on and smeared out on the slant. 



Diplococcus intracellularis meningitidis (Weichselbaum, 1887). 

 This is the organism of epidemic cerebrospinal meningitis, and is 

 frequently termed the meningococcus. The diplococcus is Gram 

 negative and biscuit-shaped and is, like the gonococcus, chiefly con- 

 tained in pus cells. It is also found free in the cerebrospinal fluid 

 withdrawn from cerebrospinal fever cases. There is a greater tendency 

 to variation in size and shape than is the case with the gonococcus, 

 which latter, in fresh material, shows a striking uniformity morpholog- 

 ically. The meningococcus is at times not abundant early in the case, 

 however, the picture may be similar to that of gonorrhoea. 



On blood-serum the colonies appear after twenty-four to forty-eight hours as 

 discrete, very slightly hazy colonies, about one-tenth of an inch in diameter. On 

 serum agar, as ascites or hydrocele agar, they grow best. Unless considerable 

 cerebrospinal fluid is transferred with the inoculating loop, they do not grow on 

 plain agar. They will grow at times on glycerine agar. The organism is very 

 sensitive to light, cold and drying. It ferments dextrose and only grows at blood 

 temperature, thus distinguishing it from the M. catarrhalis. It is scarcely patho- 

 genic for laboratory animals, with the exception of the mouse and guinea-pig, 

 when intraperitoneal injections but not subcutaneous ones give results. Intradural 

 injections give results. The cultures die out very rapidly, so that it is necessary to 



