PYOGENIC BACTERIA. 285 



to the difficulty of cultivating this micrococcus, and the importance, 

 under certain circumstances, of not making a mistake in its diag- 

 nosis, these characters are of exceptional value. 



Biological Characters. The "gonococcus" does not grow in 

 flesh infusions, in nutrient gelatin or agar, but it may be cultivated 

 upon blood serum, and, according to Bumm, grows more readily upon 

 human blood serum than upon that of the lower animals. This 

 he obtained for his experiments from the placenta of a recently de- 

 livered woman by passing two ligatures around the cord before 

 separating the child from its placental attachment, and dividing it 

 between them. But even upon blood serum obtained in this way it 

 is not a simple matter to obtain a pure culture. When other micro- 

 cocci are present, even in small numbers, they take the precedence 

 and overgrow the surface of the culture medium before the gono- 

 coccus has made any visible growth. It is therefore necessary to 

 start a culture with pus containing this micrococcus only and in 

 considerable numbers. And the pus should not be spread out in a 

 thin layer, but should be distributed upon the surface in little drops 

 or masses, in which the development commences. A temperature 

 of 30 to 34 C. is most favorable for the development of this micro- 

 coccus, and Bumm recommends the transfer to fresh culture material 

 in from eighteen to twenty-four hours. The cultures thrive best in 

 a moist atmosphere, and it is well to place the tubes containing them 

 in a large glass jar partly filled with distilled water and having a 

 tightly fitting cover. The growth under the most favorable condi- 

 tions is slow, and frequently no development occurs when pus con- 

 taining numerous gonococci is placed upon blood serum in an incu- 

 bating oven ; or after a slight multiplication development ceases and 

 the cocci undergo degenerative changes and quickly disappear. 



Cultures upon the surface of blood serum form a very thin, often 

 scarcely visible layer, with a smooth, moist, shining surface, and 

 by reflected light a grayish-yellow color. The growth at the end of 

 twenty-four hours may extend for a distance of a millimetre along 

 the line of inoculation, but at the end of two or three days no fur- 

 ther development occurs and the cocci soon lose their vitality. This 

 micrococcus, then, is aerobic. Whether it may also be a facultative 

 anaerobic has not been definitely determined, but it does not grow 

 along the line of puncture when stick cultures are made in blood se- . 

 rum. Its rapid and abundant multiplication in gonorrhoeal infection 

 of mucous membranes, and the difficulties attending its cultivation 

 in artificial media, show that the gonococcus is a strict parasite. 



Lestikow and Loffler, prior to the publication of Bumm's impor- 

 tant monograph, had reported successful results in cultivating the 

 gonococcus upon a mixture of blood serum and gelatin. Bockhart 



