MICROCOCCUS TETRAGENUS 1 57 



and very serious results follow. Cystitis caused by the gonococcus 

 is sometimes followed by infection of the kidneys. In the urethra, 

 the cocci may burrow deep beneath the epithelial cells, and set up 

 a metaplasia, or abscess formation. The purulent exudate is rich 

 in phagocytes gorged with cocci, often as many as 40 being found 

 within a cell. 



Immunity . One infection does not confer immunity against 

 further infection. There is no reliable means of producing artifi- 

 cial immunity. However, gonococcus bacterins are of some value 

 for chronic gonorrhoea. Torrey has been able to obtain from 

 rabbits an anti-serum of therapeutic value in gonorrhoeal arthritis. 



MICROCOCCUS TETRAGENUS 



Micrococcus Tetragenus. 



Morphology and Stains. Round or oval cocci; found in pairs; 

 more commonly in fours differing in size. In culture this form of 

 growth is apt to vary, and not to be characteristic. In sections of 

 human or animal tissues, tetrads only are found that are always 

 surrounded by a capsule which is stained easily by eosin. The 

 cocci are stained by Gram's method. It is not motile, and does 

 not form spores. 



Oxygen Requirements. It grows very well in the presence of 

 oxygen, and poorly without it. 



Cultures. Grows well on all common culture media. On gela- 

 tine plates its growth is characterized by small white colonies, 

 elevated, with sharp outlines. It does not liquefy the gelatine. 

 On agar it grows even more luxuriantly than on galatine. In 

 bouillon it thrives well, depositing a heavy precipitate. In milk 

 it causes acidity but no coagulation. On potato it also grows, 

 leaving a silvery streak where the inoculating needle was drawn. 



Chemical Activities. It produces acid in sugar bouillon, but 

 does not form gas, indol, or H 2 S. 



Habitat. Has never been found outside the human body; is 





