MICROCOCCUS INTRACELLULARIS MENINGITIDIS 519 



"bacteriophage" phenomena discussed in a separate section. Since 

 the extensive investigation of the autolytic properties acquired by 

 bacteria under certain conditions, there has been no investigation of 

 the meningococcus problem from this point of view. We ourselves 

 have often found meningococcus cultures to lose their viability under 

 conditions which, retrospectively, we suspect now may have been due 

 to this kind of development. It is also not unlikely that the extensive 

 autolysis of the organism in the spinal fluid may have a similar sig- 

 nificance. Storage is best carried out at incubator temperatures. At 

 room temperatures or in the ice chest, the diplococcus dies rapidly. 11 



Special Meningococcus Media. For the routine cultivation of 

 meningococcus, there are certain media which are better than others 

 and which are, therefore, described in this section. 



As a basis for meningococcus media, we like to use hormone agar 

 or hormone broth, or trypagar or trypsinized broth as described in the 

 section on media. To these basic media enriching substances are added. 

 The necessity for these enriching substances may have a more complex 

 cause than the simple addition of nutrition, since, as Lloyd has sug- 

 gested, the occasional first growth on simple media of meningococci 

 directly from the human body, may depend upon the presence of a 

 certain amount of "vitamine" furnished by the animal fluids present 

 in the exudate. The most convenient substances to add to these media 

 are blood in one form or another. Many different varieties of blood 

 are favorable, and human, horse, or rabbit blood can be most con- 

 veniently used. The blood may be defibrinated and added directly in 

 quantities of about five per cent, and if agar for plating is used, 

 melted agar is mixed with the blood and thoroughly shaken just as the 

 plates are poured. Laked blood is very convenient, and may be pre- 

 pared by mixing whole blood with about four parts of sterile distilled 

 water. This laked blood may be kept and mixed with the agar just 

 before pouring the plates, after the agar has been cooled below 50. 

 The blood may also be laked in ether and in this way can be kept sterile 

 for a long time before being added to the basic medium. Blood serum 

 and ascitic fluid can be used, but do not seem to give as good results as 

 does laked or whole blood. The addition of one-half to one per cent 

 of glucose is always favorable. The special pea-powder-blood-agar 



11 A very thorough biological study of meningococcus and related organisms 

 lias recently been made by Elser and IFuntoon (Jour. Med. Res., N. S. vol. xv, 

 1909), which may be consulted for a more detailed description of cultural 

 characteristics. 



