424 IMMUNOLOGY 



they recommended involved a number of striking departures from 

 the original technique. These differences are set forth in the 

 folloAving short paragraphs since the technique was later to form 

 the basis of the Wassermann reaction. 



Total Volume. — In the Bordet-Gengou technique the total 

 volume was 2.0 c.c. in some tubes while in others it was 1.6 and 

 1.8 c.c, respectively. Wassermann and Bruck recommended that 

 it be 5.0 c.c. in all tubes. 



Bactkrl\l Antigens. — In the original technique the antigen 

 consisted of a suspension of bacteria of which an arbitrary amount 

 was used in the test. Wassermann and Bruck recommended tliat 

 extracts of bacteria be used and that the antigenic unit be de- 

 termined by titration and that two units be used in the test. 



Complement. — Where 0.2 c.c. of guinea pig or human serum 

 was used in the original test, the modification called for 1.0 c.c. 

 of a 1 :10 dilution of guinea pig complement. Apparently an 

 arbitrary rather than a titrated amount was used in both in- 

 stances. 



Immune or Patient's Serum. — Bordet and Gengou u.sed 1.2 c.c. 

 of inactivated immune serum or normal serum in each tul^e, while 

 AVassermann and Bruck used 1.0 c.c. of a 1 :10 dilution of in- 

 activated serum. They found that large amounts of serum as 

 recommended by Bordet and Gengou are anticomplementary. 



Red Cell Suspension. — In the Bordet-Gengou technique 0.2 c.c. 

 of a 10 per cent suspension of sensitized rabbit cells was added to 

 each tube. Since the total volume, while variable, was approxi- 

 mately 2.0 c.c, the final concentration of red cells was about 1.0 

 per cent. Wassermann and Bruck added 1.0 c.c. of a 5 per cent 

 washed sheep red cell suspension to each tube, and since the total 

 volume adopted by tliem was 5.0 c.c, the final concentration would 

 likewise be 1.0 per cent. 



Hemolysin. — In the original technique the red cells were sensi- 

 tized before they were added to the tubes, while in the Wasser- 

 mann-Bruck modification the hemolysin was titrated and two units 

 were added to the tubes containing 1.0 c.c. of 5 per cent sheep cell 

 suspension. 



The Application of Complement Fixation to the Diagnosis of 

 Syphilis.— During the same year (1905) that Wassermann and 



