MICROCOCCUS CATARRHALIS 303 



37 C. In forty-eight hours colonies of the gonococcus should be 

 recognisable on the blood-agar, but not on the plain agar. 



If cultures are obtained, the fermentation tests (see below) may 

 be applied. 



(3) Complement fixation. This may be employed, using a poly- 

 valent gonococcal antigen (see Thomson, Lancet, 1918, vol. ii, 

 p. 42). 



N.B. The greatest caution must be exercised in declaring a case 

 free from infection on the ground of NEGATIVE results of the micro- 

 scopical examination. 



Micrococcus [Neisseria] catarrhalis 



This organism occurs in the nose and throat in cases of catarrh, 

 and particularly in the " influenzal cold" (see "Influenza"), in 

 bronchial catarrh, and occasionally in other conditions and in 

 well people. Morphologically it occurs in pairs and tetrads, often 

 within the polymorphonuclear leucocytes. It is Gram-negative. 

 The primary generation develops feebly on agar, but subsequent 

 generations grow fairly well, forming whitish translucent colonies. 

 Blood or ascitic media should be used for isolation. Some of the 

 fermentation reactions and a comparison with other Gram-nega- 

 tive cocci are given in the tables on pages 296 and 302. A vaccine 

 prepared with it is frequently of service in catarrhal affections of 

 the respiratory tract. 



Micrococcus [Staphylococcus] tetragenus 



This organism is frequently met with in phthisical cavities and 

 may be expectorated in the sputum, and has also been found in 

 the pus of acute abscesses. The cells occur singly (diameter 1 p), 

 in pairs, or in fours, and are enclosed within a capsule. It 

 stains with the ordinary anilin dyes and also by Gram's method. 

 On gelatin it develops slowly, with the formation of a thick, white, 

 shining growth without liquefaction. On agar the growth has 

 much the same characters, and on potato is white and viscous. 

 Inoculated into animals, particularly mice, a local abscess may 

 form, but usually a fatal general infection ensues, and the organism 

 is found in the blood and organs. 



A few cases of general infection in man have been described, 



