206 THE PRINCIPLES OF IMMUNOLOGY 



factory, but it has the same objections as obtain in the Wassermann 

 test. A human-rabbit .system may be substituted if desired. 



The test appears to be highly specific and of great clinical value 

 when properly performed Although the gonococcus and meningo- 

 coccus are closely-related organisms and may, according to Wollstein, 

 give crossed complement-fixation reactions there is no satisfactory 

 evidence that epidemic cerebrospinal meningitis in man produces con- 

 fusing complement-fixing bodies. Dixon has recently studied 840 

 tests made by Dixon and Priestly on 625 individuals. Of fifty-three 

 strongly positive reactions 90.4 per cent, had gonorrhea or a history 

 of the disease, of sixty-six moderately strong reactions 86.3 per cent, 

 were confirmed clinically, of seventy-five weakly positive reactions 72 

 per cent, were confirmed clinically, of ninety doubtful reactions 58.9 

 per cent, were clinically cases of gonorrhea. Of 341 negative reactions 

 26.1 per cent, were cases of gonorrhea in some form; of these only 

 one case was positive to a second test. Therefore, a positive test is 

 to be regarded as strong presumptive evidence of the disease, but 

 both positive and negative reactions should be controlled by sub- 

 sequent tests. 



OTHER COMPLEMENT-FIXATION TESTS 



Glanders. The complement-fixation test in this disease appears 

 to be highly specific independently of the strain of the antigenic 

 organism. Its principal application is in the disease as it affects horses. 

 The mallein test and the agglutination test are satisfactory but can be 

 supplemented by complement fixation. Occasionally it may be ser- 

 viceable in human medicine. 



Typhoid Fever. Although earlier workers obtained variable re- 

 sults, later investigations in the hands of Garbat and of Kolmer with 

 salt solution extracts of numerous strains of the bacillus, the so-called 

 polyvalent antigen, have given excellent results more particularly in 

 the second or third week of the disease or later. Blood cultures, the 

 Widal and the Dreyer tests are so much more easily performed that 

 the complement-fixation test is to be regarded as only supplementary. 

 Nevertheless, complement fixation is more likely to occur in the course 

 of the disease than as the result of prophylactic vaccination and accord- 

 ingly may gain diagnostic value. 



Smallpox. Positive results have been obtained in this disease by 

 Jobling, Sugai, Dalm, Klein, Kolmer and others. The antigen has been 

 obtained either from the lesions of vaccinia in calves or from human 

 smallpox lesions. Salt solution extracts appear to be better than alcoholic 

 extracts. In addition to the diagnostic value, the reaction adds to the 

 evidence concerning the biological identity of smallpox (variola) vari- 

 oloid and vaccinia. Our interpretation of Xylander's results indicates 

 that vaccinia in man does not lead to the establishment of complement- 

 fixing bodies over a long period of time and therefore in all probability 

 is not a true index of immunity to smallpox. The great diagnostic 



