MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 735 



be obtained anaerobically. The inost favorable reaction of artificial media is said to 

 be about 0.6 per cent acid to phenolphtbalein. On serum agar or similar suitable 

 media, colonies appear in twenty-four hours as fine slightly elevated, translucent 

 or opalescent spots frequently referred to as "dew-drop" colonies. They possess 

 a faint bluish or grayish white color with a slightly marked concentric or radial 

 striation with a scalloped margin and finely granular center. In serum broth there 

 may occasionally be a uniform clouding though, as a rule, there is a finely granular 

 sediment somewhat slimy with dear fluid above. Only in exceptional cases has 

 growth been observed in gelatin because of the unfavorable temperature. On 



Fig. isS- — Gonococci and pus cells. X 1000. {After Williams.) 



inspissated blood serum growth may sometimes be observed as discrete pale yellow- 

 ish or brownish colonies. Dextrose is changed with the development of acid but 

 no gas. Alkali is not formed in any medium by typical strains. No gas, indol 

 or pigment are formed. The toxins are intracellular and quite thermostable. 

 Resistance is very slight toward external influences. Cultures undergo rapid 

 autolytic changes and die out at room temperature, often within forty-eight hours. 

 A temperature of 41° to 45° wiU kill in a few hours. To light and drying they are 

 also very sensitive, and are rapidly killed by the ordinary disinfectants. 



Animals inoculated subcutaneously or intraperitoneally show symp- 

 toms of poisoning with suppuration and necrosis locally and may 

 succumb. 



The virulence of the organism is variable. They may apparently lie 

 dormant or at least they are very slightly active in chronic conditions 

 in one individual but set up an acute gonorrhoea when transferred 

 to a second person. 



