COCCACE^ AND THEIR PARASITIC RELATIONSHIPS 269 ■ 



serum and these types are designated as Group II. Group III 

 includes ths^ morphologically different P'neumococcus mucosus; 

 characterized by its large capsules, the viscid nature of its colo- 

 nies on culture media and of the peritoneal exudate which it 

 produces in the mouse. The remaining strains of pneumococci 

 are placed in a heterogeneous Group IV. Infections with pneu- 

 mococci of Group I are favorably influenced by the injection of 

 Type I serum. The Type II serum appears to be of some value 

 in treating infections with pneumococci of Group II. No thera- 

 peutic serum _ has been produced for Group III and the sera 

 obtained in Group IV are potent against only the particular strain 

 employed for immunization of the animal. Determination of 

 the Group of the infecting pneumococcus should, therefore, pre- 

 cede the therapeutic use of the serum. 



For type determination^ the sputum should be obtained from 

 "the deeper air passages under immediate supervision of the bac- 

 teriologist and should be examined immediately. Microscopic 

 examination of preparations stained by (i) Gram's method, (2) 

 Ziehl-Neelsen method and (3) Hiss capsule stain should be done. 

 Pneumococcus mucosus shows •wide capsules in both the Gram and 

 the Hiss preparations. A piece of sputum, volume about 0.2 

 c.c, is washed through four changes of salt solution in Petri dishes, 

 placed in a mortar, ground up and emulsified in about i c.c. of 

 salt solution, which is added drop by drop. About 0.5 c.c. of 

 this suspension is injected intraperitoneally into a white mouse. 

 The common sputum organisms which grow in the peritoneal 

 cavity of the mouse are the pneumococcus, the influenza bacillus. 

 Micrococcus catarrhalis, staphylococci and streptococci. The 

 former two also invade the blood stream. After 5 to 24 hours the 

 mouse is killed and the peritoneal fluid and heart's blood streaked 

 on blood agar plates. Gram stain and Hiss capsule stain of the 

 peritoneal exudate are examined. Then the peritoneal fluid 

 is washed out with s c.c. of salt solution and the suspension is 

 transferred to a centrifuge tube, whirled at low speed to throw 



' Blake, F. G.: Journ. Exp. Med., 1917, 26, p. 67. 



