126 IMMUNE SERA 



nor as constant results as does the Wassermann 

 reaction. 



The Hecht-Weinberg modification is so arranged 

 as to make use of the natural amboceptor and of the 

 complement normally present in the patient's 

 serum. Inasmuch as complement is a labile sub- 

 stance which varies both in its fixing power and in 

 its strength from day to day, this test can only be 

 accepted in cases where the result is negative. 



A number of chemical tests for the diagnosis of 

 syphilis have appeared in the literature, but it can- 

 not be said at this time that any of them can be 

 used with safety. 



Deflection of Complement. In the use of 

 antitoxic sera, experience has shown that the em- 

 ployment of a large dose is of paramount importance. 

 So far as the antitoxic action is concerned, one 

 cannot do harm by giving a large excess. Concern- 

 ing the action of bactericidal sera, however, the 

 literature contains a number of examples which 

 indicate that here an excess of immune serum is 

 occasionally injurious. Perhaps the earliest pro- 

 tocol of this kind, is that published by Loeffler and 

 Abel, 1 on their experiments with bacillus coli and a 

 corresponding immune serum. Out of 19 guinea 

 pigs which had been inoculated with the same 

 amount of culture and had received varying amounts 

 of immune serum, only six animals were protected, 



1 Loeffler and Abel, Centbl. Bact., 1896, Vol. xix, p. 51. 



