166 
Dourine 
(2) Titration of Complement. 
Prepare (1) a stock dilution of guinea-pig complement and (2) a 
suspension of sheep’s corpuscles, as in the previous titration. 
Also (3), an haemolytic serum (amboceptor) dilution, so that 1-0 c.c. 
of the diluted serum contains two amboceptor units. For example, 
if the value of one unit is 0-0005, then 0-001 will be that of two units, 
the dilution being accordingly 1: 1000. 
The titration of complement is of the utmost importance and requires 
the greatest accuracy, as already indicated. Until one has become 
familiar with the technique and expert in reading the reactions the 
titration is best carried out in a double set, the second set having one- 
half of the amount of each reagent used in the first set, the one serving 
as a check to the other. 
The two sets are arranged as follows: 
Titration of Complement. 
First set 
Second set 
Salt 
solution 
c.c. 
Haemol. 
Complement serum 
c.c. c.c. 
Salt 
solution 
c. c. 
Complement 
c.c. 
Haemol. 
serum 
C.C. 
Tube No. 1 
2-0 
0-3 (1 : 20) 10 
1-0 
0-15(1 : 
: 20) 0-5 
99 
2 
2-0 
0-4 10 
10 
0-2 
0-5 
99 
3 
2-0 
0-45 10 
1-0 
0-225 
0-5 
99 
4 
2-0 
0-5 1-0 
1-0 
0-25 
0-5 
99 
5 
2-0 
0-55 10 
1-0 
0-275 
0-5 
99 
6 
2-0 
0-6 1-0 
1-0 
0-3 
0-5 
99 
7 
2-0 
0-65 1-0 
10 
0-325 
0-5 
99 
8 
2-0 
0-7 1-0 
10 
0-35 
0-5 
J 9 
9 
2-0 
0-8 1-0 
1-0 
0-4 
0-5 
99 
10 
2-0 
1-0 0-5 
1-0 
0-5 
0-25 
99 
11 
3-0 
10 
— 
— 
— 
99 
12 
3-0 
1-0 — 
2-0 
— 
— 
Add 1 e.o. red cell sus- Add 0-5 c.c. red cell sus¬ 
pension to each tube. pension to each tube. 
Mix well (avoiding undue frothing). 
Incubate at 38-39° C. 
Agitate the mixtures again by shaking the racks after ten minutes 
incubation. 
Read the reactions one hour later. 
Tube No. 10 controls the original haemolytic titration, only one 
unit of amboceptor being used with an excess of complement. In this 
tube complete haemolysis should occur. 
