Streptococcus Tetragenus 



coccus tetragenus can sometimes be found in normal saliva, tuber- 

 culous 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 abscesses which complicate tuberculosis. It was dis- 

 covered by Gaffky.* 



Morphology. The cocci are rather large, measuring about i jj, 

 in diameter. In cultures they do not show the regular arrange- 

 ment in tetrads as constantly as in the blood and tissues of animals, 

 where they occur in groups of four surrounded by a transparent 

 gelatinous capsule. 



Fig. 112. Micrococcus tetragenus in spleen of infected mouse. (From Hiss 

 and Zinsser," Text-Book of Bacteriology," D. Appleton & Co., Publishers.) 



Staining. The organisms stain well by ordinary methods and 

 beautifully by Gram's method, by which they can best be demon- 

 strated in tissues. 



Isolation. The organism can be isolated by inoculating a white 

 mouse with sputum or pus containing it, and after death recovering 

 it from the blood. 



Cultivation. It grows readily upon artificial media. Upon 

 gelatin plates small white colonies are produced in from twenty- 

 four to forty-eight hours. Under the microscope they appear 



* "Archiv. f. Chirurgie," xxvin, 3. 



