272 INFECTION AND IMMUNITY 



quantity necessary to produce complete hemolysis of 1 c.c. of a five 

 per cent emulsion of blood cells, in the presence of two units of ambo- 

 ceptor. When titration is omitted 0.1 c.c. may be used in routine work, 

 and is sufficiently accurate. 



2. Hemolytic amboceptor: rabbit serum hemolytic for sheep 

 corpuscles. Inactivated and titrated as for Wassermann test. Two 

 units are used in the test. 



3. A five-per-cent emulsion of sheep corpuscles in salt solution, pre- 

 pared as for Wassermann test. 



4. A highly potent typhoid antiserum obtained from an immunized 

 rabbit. In this case the smallest quantity of the immune serum which 

 will cause the fixation of complement in the presence of an emulsion or ex- 

 tract of typhoid bacilli is determined by experiment. The bacillary emul 

 sion is prepared by scraping the growth from twenty-four-hour agar slant 

 cultures, drying it, and macerating in a mortar with salt solution until 

 a slightly opalescent emulsion is formed. A series of tubes is prepared 

 into each of which is placed 0.1 c.c. of the emulsion of bacteria, 0.1 c.c. 

 of fresh guinea-pig serum, as complement, and gradually diminishing 

 quantities of the inactivated specific immune serum, ranging fromO.l c.c. 

 downward. These tubes are left for one hour at 38° to 40° C, and, 

 following this, there are added the required quantities of red blood 

 cells and hemolytic immune serum. The smallest quantity of im- 

 mune serum which has completely inhibited hemolysis is the unit 

 and a quantity slightly greater than this should be used in the actual 

 test.i 



5. Serum from the patient, inactivated at 56° C. for twenty 

 minutes. 



In the actual test a series of tubes are prepared each of which con- 

 tains: 



1. Complement, the determined quantity or 0.1 c.c. 



2. Antiserum, the determined quantity. 



3. Diminishing quantities of the serum to be tested for antigen be- 

 ginning with 1 c.c. 



Salt solution is added for dilution to 3 c.c. 



These substances are left together at 40° C. for one hour and then 

 the required quantities of amboceptor and red cells are added. The 

 reaction is controlled by tubes containing the same ingredients without 



1 Mailer, " Technik d. serodiagnos. Methoden," Jena, 1909; Leidke, " Zur Kennt- 

 niss d. Komplemente," Wiirzburg, 1908. 



