CULTURAL CHARACTERISTICS 



639 



Single colonies. To obtain single colonies Wertheim's agar may be poured 

 into Petri dishes and after solidifying sown by the parallel stroke method 

 (p. 81). After incubating for 24 hours at 37 C. small, punctiform, viscous 

 and transparent colonies appear ; these increase in size and about the second 

 or fourth day may be as large as a pin's head and hemispherical ; examined 

 with a lens, their edges are seen to be slightly sinuous and their centres whitish, 

 semi-opaque or even opaque (Wildbolz). 



Krai's agar. Krai substitutes calf for human serum in Wertheim's agar. 



Heiman's agar. Proceeding as above, mix two parts of ordinary agar and one 

 part of pleural fluid sterilized by discontinuous heating (p 47). The medium 

 should be neutral and if the serum be alkaline it should be added to a slightly acid 

 agar. 



Wildbolz' agar. Heffter having shown that fluid from ovarian cysts which 

 contains a large amount of pseudo-mucin may with advantage be used instead of 

 ascitic fluid in the preparation of media for the gonococcus, Wildbolz recommends 

 an agar containing pseudo-mucin. 



Melt some ordinary agar and add 5 per cent, of finely powdered pseudo-mucin. 1 

 Heat the mixture to 100 C. for an hour, filter while hot, distribute into tubes and 

 sterilize at 100 C. 



Abe's agar. Take 500 grams of beef, cut off all the fat, mince and macerate 

 in 1 litre of water for 20 hours in the ice chest. Filter 

 through paper, then through a Chamberland bougie. 



To the nitrate add ordinary nutrient agar which has 

 been melted and cooled to 50 C. in the proportion of two 

 parts of meat extract to five of agar. Distribute in tubes 

 or Petri dishes. The medium is transparent and very suit- 

 able for the growth of the gonococcus. 



Pfeiffer's blood-agar. This medium is prepared by 

 simply spreading a few drops of sterile fresh human blood 

 on agar plates. The characteristics of the growth are the 

 same as those on Wertheim's agar (Ghon and Schlagen- 

 haufer, Abel). 



Bezanpon and Griffon's blood-agar (p. 53). This is a 

 very useful medium for growing the gonococcus. 



Tubes of blood-agar sown with a liberal amount of 

 gonorrhceal pus and incubated at 37 C. show, after 24 

 hours, a copious growth consisting of flat, rounded, moist, 

 transparent, lustrous colonies of variable size, sometimes 

 coalescing to form a viscous layer with pinked edges. The 

 medium which is in the first instance red becomes chocolate- 

 coloured as growth proceeds, the colonies being delicately 

 picked out in white. 



Nasstikoff's agar. This medium is recommended by 

 Steinschneider for the cultivation of the gonococcus . Collect 

 the yolk of an egg in a sterile manner (p. 54) and mix it 

 thoroughly with three times its volume of sterile water. 

 Liquefy a few tubes of sterile agar each containing about 

 6 c.c., and when they have cooled to 45 C. add 2 c.c. of the egg emulsion 

 to the contents of each tube, being careful to avoid contaminations. Mix 

 carefully, slope the tubes and allow to set. 



Leipschutz" agar. Prepare a 2 per cent, solution of the substance sold by 

 Merck as " powdered egg-albumin." To 100 c.c. of this solution add 20 c.c. 

 of deci-normal soda solution. Stand for half an hour and filter through 



FIG. 302. Gonococ- 

 cus. Stroke culture on 

 glycerin-ascitic-agar (3 

 days at 37 C.). 



1 Pseudo-mucin is obtained by precipitating the fluid from ovarian cysts with alcohol. 



