308 AGGLUTININS 



should be included; also a culture control prepared with normal salt 

 solution. After gentle mixing and standing at room temperature for 

 twenty-four hours the results are read; positive results are indicated 

 by complete clearing of the tube with tjie micro-organisms in flakes or 

 granules, either clinging to the sides of the tube as granular material or 

 at the bottom as flaky granular sediment. 



The Agglutination Test in the Differentiation of Pneumococci. 

 The investigations of Neufeld and Handel, and particularly of Cole, 

 Dochez, and their associates in the Rockefeller Institute, have resulted 

 in the grouping of pneumoccoci into four groups on the basis of agglutina- 

 tion and protective tests. Group III is composed of pneumococci 

 belonging to the type of pneumococcus mucosus, and an efficient anti- 

 serum has not yet been produced; Group IV is composed of all pneu- 

 mococci not falling into the first three groups. 



Tne agglutination test is conducted for the purpose of determining 

 the presence of types I or II; in case either is present and it is decided 

 to administer an immune serum, the serum corresponding to the type 

 of infection must be given. Either a macroscopic or microscopic technic 

 may be employed; as it is advisable to learn the results as quickly as 

 possible, the latter saves time, although it is generally considered as 

 being less accurate than the former. 



1. Sputum coughed up from the lung is collected, washed with sterile 

 salt solution, and 1 c.c. injected into the peritoneal cavity of a mouse. 



2. If sputum is not obtainable, a culture may be secured by puncture 

 of the lung after anesthetizing the skin with sterile eucain solution. 

 With a sterile syringe carrying 2 c.c. of warm sterile salt solution and 

 medium-sized needle a puncture is made into the consolidated area and 

 exudate secured which is injected into the peritoneal cavity of a mouse. 



3. Four to eight hours later the mouse is killed with ether and the 

 peritoneum washed out with 5 to 10 c.c. of normal salt solution. This 

 emulsion is briefly centrif uged to throw down cells and the supernatant 

 fluid transferred to a second centrifuge tube followed by rapid and thor- 

 ough centrifuging to throw down the pneumococci. The sediment of 

 cocci is then suspended in sufficient normal salt solution to give an even 

 emulsion of proper density. The supernatant fluid may be used in 

 the precipitin test of Blake as described on page 321. 



4. Macroscopic tests are prepared by mixing in small clear test-tubes 

 equal parts (0.5 c.c.) of bacterial suspension and antipneumococcus sera 

 of types I and II undiluted and diluted 1 : 5 with salt solution. The 

 final dilutions are 1 : 2 and 1 : 10. These mixtures are incubated at 



