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382 PATHOGENIC MICROORGANISMS 



or the swine-serum-nutrose medium of Wassermann l may occasionally 



be used with success. 



Plates may be made by smearing for enrichment a drop of blood 



from the finger over the surface of agar in the manner of Pfeiffer's 



method for influenza-bacillus cultivation. Inoculations from gonorrheal 



material are best made by surface 

 smearing upon plates, since the gono- 

 coccus grows best in the presence of 

 free oxygen. Growth becomes more 

 luxuriant after prolonged cultivation 

 upon artificial media. The most 

 favorable reaction of media is neu- 

 trality or slight acidity. 



When the gonococcus has been 

 successfully cultivated from pus upon 

 media without serum additions, the 



success has probably been due to the 

 FIG. 81. GONOCOCCUS. Smear . , ,, 



, substances carried over in the pus. 



from pure culture. ... 



The ease of cultivation differs con- 

 siderably with different strains of gonococci. Some grow very heavily 

 after first isolation, but the majority show a very delicate growth 

 even on rich ascitic glucose agar. After several generations of growth 

 on artificial media, however, the organism develops with increasing ease 

 and on simpler media. It may eventually be cultivated on plain agar, 

 especially when this is made of veal infusion. Recently a medium upon 

 which gonococci after first cultivation can be grown with ease has been 

 recommended by Edward B. Vedder. 2 The medium consists of a 

 1 . 5 to 1 . 75 per cent agar made with beef infusion neutral to phenol- 

 phthalein, and after clearing, 1 per cent of corn starch added. The corn 

 starch is best added after grinding with a little agar to avoid clumps, 

 this then being poured into the bulk of the agar and thoroughly mixed. 

 The medium should be sterilized at not over 15 Ibs. pressure to avoid 

 changes in the starch. Recently we have isolated several strains of 

 gonococci which grew very heavily on simple media without ascitic 

 fluid in the second culture generation. 



1 Wassermann, Berl. klin. Woch., 1897. 



(Fifteen c.c. swine-serum, 35 c.c. of water, 3 c.c. glycerin, with two per cent 

 nutrose. The nutrose is dissolved by boiling and the solution sterilized. This is then 

 added to agar, in equal parts, and used in plates.) 



2 Vedder, Jour. Infec. Dis., May 15, 1915, xvi, 385. 



