TECHNIC OF WASSERMANN REACTION. 287 



required for the test will be described and then 

 their application to the test. 



Sheep's corpuscles may be obtained from the 

 jugular vein of the animal. The blood is defibri- 

 nated and washed by centrifugation with salt 

 solution, the salt solution being changed twice. 

 A 5 per cent, suspension of these corpuscles in 

 0.85 per cent, salt solution is used for the test. 



Inactivated hemolytic serum for sheep's cor- 

 puscles is prepared by immunizing a rabbit against 

 sheep's corpuscles. The animals should be injected 

 intraperitoneally with washed corpuscles made up 

 to the volume of blood from which they were 

 taken, by the addition of salt solution. At least 

 four or five injections should be given at intervals 

 of from four days to a week, and with amounts 

 beginning with 2 c.c. and ending with from 12 to 

 20 c.c. The animal should not be bled before ten 

 days after the last injection. Blood is obtained 

 from the marginal vein of the ear and allowed to 

 clot. The serum is then removed, heated to 56 

 C. for one-half hour and standardized as follows : 

 Varying graded amounts of the inactivated serum 

 plus 0.1 c.c. of complement (fresh guinea-pig 

 serum, best obtained by aspiration from the heart), 

 are added to each of a number of tubes containing 

 1 c.c. of 5 per cent, sheep's corpuscle suspension. 

 The tubes are incubated for one hour and that tube 

 noted in which the smallest amount of amboceptor 

 (inactivated rabbit's serum), produced complete 

 hemolysis. This is called the hemolytic unit of 

 amboceptor. 



The antigen is prepared by the extraction of 

 minced syphilitic or normal liver, with 10 volumes 



