550 PATHOGENIC MICROORGANISMS 



but has marked preference for aerobiosis. The optimum temperature 

 is 37.5 C. Growth ceases above 38.5 and below 30. 



Upon suitable media colonies appear as extremely delicate, grayish, 

 opalescent spots, at the end of twenty-four hours. The separate colo- 

 nies do not tend to confluence and have slightly undulated margins. 

 Touched with a platinum loop their consistency is found to be slimy. 

 In fluid media, growth takes place chiefly at the surface. 



Types of the Gonococcus. As in the case of so many other organisms, 

 it has been found that the Gram-negative diplococci which cause gon- 

 orrheal infections are not a single type, but must be regarded as rep- 

 resenting a group, including many closely related,' but antigenically 

 differentiable subgroups. Such subgrouping of species formerly regarded 

 as homogeneous has been a very natural development of the more 

 intensive study of serum reactions, incident to diagnostic agglutination 

 and complement fixation, and to the control of specific therapy. Torrey 9 

 and Teague and Torrey 1 in 1907 showed that the gonococcus group is 

 not homologous, but that agglutination and agglutinin absorption 

 divided this group into at least three separate subtypes. Agglutinin 

 absorption seemed to show more types than complement fixation,- a 

 matter which we ourselves would rather expect at the present day 

 because of the almost universal experience that complement fixation 

 reactions are not as strictly specific as agglutination. Torrey's claims 

 have been to some extent misquoted in the past ten years, in that he 

 himself never supposed that his ten strains represented the entire gon- 

 ococcus group. In 1910 Watabiki n made a similar study of the gon- 

 ococcus group, and studying a limited number of strains, confirmed the 

 heterogeneous nature of the group by referring to them as " compara- 

 tive but not distinctive differences between individual strains." In 

 1915 Louise Pearce 12 made a comparison between gonococci isolated from 

 adult males and from the vulvovaginitis of children. She came to the 

 conclusion that strains from these two sources constituted fairly definite 

 serologically distinct groups, that at least there was a relative distinc- 

 tion between the two types. This, in view of the important sanitary 

 problem involved in these infections in children, would be of great 

 importance if confirmed. We will refer to it again below. More 



9 Torrey, Jour. Med. Res., 16, 1907, 329. 



10 Teague and Torrey, Jour. Med. Res., 17, 1907, 223. 

 Watabiki, Jour. Infec. Dis., 1910, 7, 159. 



12 Pearce, Jour. Med. Res., 21, 1915, 289. 



