A STUDY OF FIXATION REACTIONS. 



365 



Instead of recording the presence or absence of haemolysis and its degree, Meier' 

 uses two quantities of antibody 0.1 and 0.2 cubic centimeter and follows Citron's 

 scheme of interpreting the result directly in terms of deflection without first 

 noting haemolysis. The degree of deflection varies according to the combination 

 of results obtained with these two quantities as follows: 



Serum. 



Designation of 

 strength of 

 reaction. 



.0.2. 



0.1. 



Complete blocking 



Complete blocking 



Incomplete blocking... 



+ + + + 

 + + + 



+ + 







.. do.. 







4. Miscellaneous. 



Miihsam(lO) notes that the negative test must be repeated after several days 

 as the complement binding substances are not always constant in amount, and 

 Wassermann(2) states that any specific serum, which of itself precipitates human 

 albumen, is useless for the deflection test. This refers to the serum of monkeys 

 previously immunized with luetic substances. 



II. TECHNIQUE OF DEFLECTION TEST IN FORENSIC PRACTICE AND IN THE 

 DIFFERENTIATION OF BLOOD. 



The application of the deflection test for this purpose is essentially the same 

 as in the case just considered. The known quantities are usually the hemolytic 

 complex, the complement serum, and the specific antibody obtained by immunizing 

 a rabbit with human serum or other known material. The unknown quantity is 

 the antigen, usually a blood clot or blood stain. 



Neisser and Sachs(H, 12, 13) adopted the following technique in diagnosing 

 blood clot or blood stain. They employ as the hemolytic complex a 5 per cent 

 suspension of sheep's corpuscles freed from serum, and the serum of a rabbit 

 immunized against ox corpuscles which is always strongly hemolytic for sheep's 

 corpuscles also. The serum is completely clarified by centrifugation and inactiv- 

 ated by heating to 56° for half an hour. 



The antihuman serum should be of such a strength that 0.01 cubic centimeter 

 will deflect when treated with 0.0001 of human serum. In general they recommend 

 of such a serum the use of 0.02 cubic centimeter as a basic amount for future 

 work and further (12) that the amount of human serum used in the test should 

 be small, 0.0001 being a good dose for testing. 



In the deflection experiment,. they(ll) use 1 cubic centimeter of a 5 per cent 

 suspension of serum-free sheep's corpuscles in 0.85 per cent salt solution treated 

 previously with 0.0015 of hemolytic serum, which is just twice the lytic dose. 

 In other test tubes quantities of human serum varying from 0.01 to 0.000001 are 

 mixed 0.1 of antihuman serum and 0.05 of guinea-pigserum; 2 after standing for 

 an hour these tubes are treated with the sheep's corpuscles previously laden with 

 ■ amboceptor. The mixture is placed in the incubator two hours, transferred to 

 ice, and the results noted in the morning. 



- In a later report they use 0.1 cubic centimeter of guinea-pig serum. 



