266 



INFECTION AND IMMUNITY 



presence of one unit of amboceptor, 0.1 c.c. of guinea-pig's complement 

 is required to produce hemolysis, by using four, eight, and twenty units 

 of amboceptor, complete hemolysis is obtainable with one-third, one- 

 fifth, and one-tenth of the 0.1 c.c. of complement, respectively. For 

 this reason an excess of amboceptor might result in complete hemolysis 

 in a test, if a small fraction of the complement were left unfixed by 

 the syphilitic antibody. Another result of an excess of amboceptor 

 would consist in a partial dissociation of the complement from its com- 

 bination with the antigen-antibody compound. As Noguchi puts it, 

 "a quantity of syphihtic antibody just sufficient to fix 0.1 c.c. of the 

 complement against two units of the amboceptor is no longer efficient 

 in holding back the complement from partial liberation against the 

 influence exerted by more than four units of the amboceptor." 



From these considerations it follows that the serum from rabbits 

 immunized against sheep corpuscles must, in each case, be titrated in 

 order to determine the hemolj^tic unit. For this purpose a number of 

 mixtures are made in test tubes, containing each 0.1 c.c. of complement 

 (fresh guinea-pig serum), 1 c.c. of a 5 per cent emulsion of sheep's cor- 

 puscles, and diminishing quantities of the inactivated hemolytic serum, 

 thus : 



hemolysis. 



hemolysis. 



hemolysis. 



J , J .003 c.c. = complete hemolysis. 



""' ' ' hemolysis. 



.1 c.c. of 

 complement 



fresh 

 guinea-pig 



serum. 



y +H 



1. c.c. 



of 5 per 

 cent 

 emul- 

 sion 



sheep's 



corpus- 

 cles. 



Inac- 

 tivated 

 hemo- 

 lytic 

 serum. 



c.c. = complete 



c.c. = complete 



c.c. = complete 



c.c. = complete 



c.c. = complete 

 .0009 c.c. = partial hemolysis 

 .0005 c.c. = no hemolysis. 

 .0003 . c.c. = no hemolysis.^ 



.01 



.009 



.005 



.003 



.001 



In the given case, 0.001 c.c. of the serum represents one unit, and 

 0.002 c.c, two units, is the quantity to be used for each test. 



III. The Complement. — ^The complement for the "Wassermann re- 

 action is used in the form of fresh guinea-pig serum. This may be 

 obtained in one of the following ways: A guinea-pig may be killed by 

 an inoision in the throat and the blood allowed to flow into a large 

 Petri dish. This is set away in the ice chest until clear beads of serum 

 have formed upon the surface, and these are then carefully removed 

 with a pipette. The writers have found it convenient, however, to 

 anesthetize the guinea-pigs, then, by a longitudinal incision into the 



' In each tube the volume of the mixture should be made up to 5 c.c. with 0.85 

 per cent salt solution. 



