358 MARSHALL AND TEAGTJE. 



It can be seen from what has preceded, that for the specific comple- 

 ment deflection phenomenon we require : 



1. A hemolytic complex consisting of (a) specifically hemolytic serum, (6) 

 corresponding homologous red blood corpuscles. 



2. Fresh serum containing free complement. 



3. An antigen. 



4. An antibody specific for the antigen. 



If 2, 3, and 4 are brought together for an hour and are then added 

 to 1, no haemolysis occurs as the complement in 2 has been "deflected" 

 during the union of 3 and 4. Knowing that this reaction always occurs, 

 the phenomenon can be used for purposes of diagnosis, either of the 

 antigen, (3), or of the antibody, (4). 



The deflection test has been applied to three main subjects : 



I. In the diagnosis of syphilis. 



II. To supplement the precipitin reaction in the forensic diagnosis of minute 

 traces of blood, and in the differentiation of blood of various species and sub- 

 species. 



III. In the diagnosis of bacteria and of bacterial diseases. 



Iii a former paper one of us (Marshall^) ) traced the origin and 

 development of the deflection method. The present article will deal 

 in detail with (1) the technique and its modifications, (2) the inter- 

 pretation of positive and negative results, (3) the range of application 

 of the method, (4) its diagnostic value, and (5) lipoidal and non- 

 specific deflections. We will also describe a comparative study of this 

 and the precipitin method. 



I. TECHNIQUE FOE THE SERUM DIAGNOSIS OF SYPHILIS. 



1. Preparation of Materials. 



a. the ii .emolytic complex. 



a. The hmmolytio serum. — All observers have used the senim of rabbits im- 

 munized against the erythrocytes of sheep. Wassermann, Neisser, Bruck, and 

 Schucht(2) recommend using a serum of which from 0.001 to 0.002 cubic centi- 

 meters dissolves 1 cubic centimeter of a 5 per cent suspension of sheep's corpuscles 

 when treated with 1 cubic centimeter of a 0.1 dilution of guinea pig serum. Of 

 this he used twice the exact dissolving dose with each cubic centimeter of 5 per 

 cent sheep's corpuscles. Meier(3) and Michaelis and Lesser(4) use and recommend 

 three times the exact dissolving dose of amboceptor. 



Wassermann (2) remarks that the limits of the hemolytic amboceptor must be 

 determined from time to time. The avidity of complement for the amboceptor 

 varies with the particular immune serum. When the serum grows old. it of 

 itself causes deflection and under these circumstances it can only be used by 

 treating the corpuscles with it and then centrifugating and suspending the 

 corpuscles in fresh salt solution before adding complement. 



b. The red blood corpuscles. — The authors quoted(2) note that the corpuscles 

 must come from a healthy sheep which has not been bled too frequently. After 

 frequent bleedings, the corpuscles become too fragile for use. The blood must be 

 defibrinated, and the corpuscles washed and centrifugated until entirely free from 

 serum, and a 5 per cent suspension made in 0.S5 per cent salt solution. 



c. The complement. — The complement, according to the same authors(2), must 



