GONOOOCCUS. 295 



causing no reddening whatever of blue litmus paper ; 

 and, finally, that the Petri dishes containing the solidi- 

 fied medium on which the cultures are growing are best 

 kept bottom upward, so as to prevent water of con- 

 densation collecting on the surface. By the use of the 

 above medium he has cultivated the gonococcus from 

 about one hundred different cases. 



If transplanted from the original culture to either 

 glycerin-agar-agar or to LofSer's serum-mixture, a 

 growth is sometimes observed, more often in the latter 

 than in the former, but of so feeble a nature that these 

 substances cannot be regarded as suitable for its culti- 

 vation. As a rule, development does not occur on 

 glycerin-agar. 



Microscopic examination of colonies of this organism 

 reveals the presence of a diplococcus somewhat larger 

 than the ordinary pyogenic cocci. The opposed sur- 

 faces of the individual cells that comprise the couplets 

 are flattened and separated by a narrow slit. At times 

 the cocci are arranged as tetrads. 



This organism cannot be gro\vn at a temperature 

 lower than that of the human body, and cultures that 

 have been obtained by either of the favorable methods 

 are said to lose their vitality when kept at ordinary 

 room-temperature for about two days. 



It is killed in a few hours by drying. 



Cultures retain their vitality under favorable condi- 

 tions of nutrition, temperature, and moisture for from 

 three to four weeks. 



This organism is without pathogenic properties for 

 monkeys, dogs, and horses, as well as for the ordinary 

 smaller animals used for this purpose in the laboratory. 



