CHAPTER XII. 

 TETRAGENUS. 



MICROCOCCUS TETRAGENUS 



General Characteristics. Large, round, encapsulated cocci, regu- 

 larly associated in groups of four, forming tetrads. They are non- 

 motile, non-flagellated, non-sporogenous, non -liquefying, non-chromo- 

 genic, non-aerogenic, aerobic and optionally anaerobic, pathogenic 

 for mice and other small animals, and stain well by all methods, in- 

 cluding that of Gram. 



Fig. 167. Micrococcus tetragenus in pus from a white mouse. X 615 



(Heim). 



A large micrococcus grouped in fours and known as Micro- 

 coccus tetragenus (Fig. 167) can sometimes be found in 

 normal saliva, tuberculous sputum, and - more commonly 

 in the contents of the cavities of tuberculosis pulmonalis. 

 It sometimes occurs in the pus of acute abscesses, and may 

 be of importance in connection with the pulmonary ab- 

 scesses which complicate tuberculosis. It was discovered by 

 Gaffky.* 



Morphology. The cocci are rather large, measuring 

 about i fi in diameter. In cultures they do not show the regu- 

 * "Archiv fur Chirurgie," 28, 3. 



