﻿IMMUNITY RESEARCH. 345 



ideas of complement must be revised extensively, both Ehrlich's and 

 Bordct's hypotheses failing to account for the conditions which he met 

 with. Pfeiffer and Moreschi(30) and Friedberger and he (10) sup- 

 posed that the disappearance of complement was in some way brought 

 about by the union of precipitin and precipitable substance and varied 

 with the amount of precipitation. They found that deflection occurs 

 not only in vitro but also in vivo. They concluded that the phenomena 

 formerly explained as depending upon the action of anti-complements 

 and anti-amboceptors are actually due to complement deflection. 



Sachs (32), replying in 1905 to Gay, worked over some experiments 

 of Pfeiffer and Friedberger and concluded that the phenomenon of 

 deflection is not due to precipitation, but is a function of the union of 

 amboceptor with its corresponding anti-genetic substance. The deflec- 

 tion occurs even when no precipitate is formed and varies independently 

 of the amount of precipitate, a result also obtained by Klein (17). Was- 

 sermann and Bruck(35) also point out that old bacterial extracts no 

 longer precipitate, but still deflect and that the same holds true of tuber- 

 culin and anti-tuberculin. The Neisser-Wechsberg studies and one by 

 Lipstein also supports Sachs's contention. 



From the first, the phenomenon of deflection has been used in prac- 

 tical diagnosis. Bordet and Gengou elaborated a delicate test for the 

 demonstration of anti-bodies specific for various bacteria. Subsequently, 

 in 1902, Gengou (15) widened the application of this method, making 

 it available for the determination of the presence of anti-bodies for the 

 most diverse albuminoid solutions, such as milk, egg, etc. JSTeisser and 

 Sachs (26, 27) employed the test for recognizing not the anti-body but 

 the antigen, using their technique with special success in detecting 

 minute traces of blood, and being able from these traces to determine 

 the species from which the blood was derived. They advise the adop- 

 tion of the method in forensic medicine, to supplement the precipitin 

 test, and make mention of three cases in which they employed it. The 

 advantages of the deflection method are: First, that it acts as a control 

 for the precipitin method ; second, that haemolysis is a much more definif e 

 index than minute precipitation; third, that an opalescent serum is 

 available for use; fourth, that it is not necessary to have such high 

 potency serum as is needed in the precipitin test and that it is not 

 necessary to wait for the clearing of the serum, which is so tedious in 

 the older test. 



During the course of 1905 and 1900, Wassermann and his co-workers 

 have given a new application to this technique. They found that dis- 

 solved bacterial substances could be detected as readily as bacterial emul- 

 sion (Med. Klin. '05), and they were able to demonstrate minute traces 

 of bacterial substance in blood derived from individuals suffering from 

 various infections. By modifying the technique they were also able to 



