CULTIVATION OF GONOCOCCUS. 191 



with a watery solution of any of the basic aniline dyes 

 methylene-blue, fuchsin, etc. It is, however, easily decolor- 

 ised, and it completely loses the stain by Gram's method 

 an important point in the microscopical examination. 



Cultivation of the Gonococcus. This is attended with 

 some difficulty, as the suitable media and conditions of 

 growth are somewhat restricted. The most suitable media 

 are solidified blood serum (especially human serum and 

 rabbit's serum), "blood agar," and Wertheim's medium, 

 which consists of one part of fluid serum, added to two 

 parts of liquefied agar at a temperature of 40 C., and then 

 allowed to solidify by cooling. The serum may be obtained 

 from the blood of the human placenta ; pleuritic or other 

 effusion may also be used. Growth takes place best at the 

 temperature of the body, and ceases altogether at 25 C. 

 Cultures are obtained by taking some pus on the loop of 

 the platinum needle and inoculating one of the media 

 mentioned by leaving minute quantities here and there on 

 the surface. The medium may be used either as ordinary 

 " sloped tubes " or as a thin layer in a Petri's capsule. The 

 young colonies are visible within forty-eight hours, and 

 often within twenty-four hours. They appear around the 

 points of inoculation as small semi-transparent discs of 

 irregularly rounded shape, the margin being undulated and 

 sometimes showing small processes. The colonies vary 

 somewhat in size and tend to remain more or less separate. 

 They generally reach their maximum size on the fourth or 

 fifth day, and are usually found to be dead on the ninth 

 day, sometimes earlier. On the medium of Wertheim 

 the period of active growth and the duration of life are 

 somewhat longer. Even if impurities are present, pure 

 sub-cultures can generally be obtained by the above method 

 from colonies of the gonococcus which may be lying 

 separate. In the early stage of the disease the organism is 

 present in the male urethra in practically pure condition, 

 and if the meatus of the urethra be sterilised by wash- 

 ing with weak solution of corrosive sublimate and then 

 with absolute alcohol, and the material for inoculation be 



