142 THE METHOD OF COMPLEMENT FIXATION. 



patients than the agglutination test. Nevertheless, this entire complement 

 fixation method remained unheeded for several years. 



Moreschi (at Pfeiffer's institute), while conducting some theoretical studies concerning 

 the nature of anticomplements, i.e., such substances which tend to neutralize the action 

 of complements, discovered anew, that by the mixture of a soluble proteid with its anti- 

 proteid serum the existing complement disappeared. This, as has been seen, can be 

 explained by the presence within the immune serum, of bodies similar to Gengou's 

 amboceptors. Moreschi, however, stated that the complement disappeared because it 

 was thrown to the bottom mechanically, by the occurrence of precipitation. Such a 

 physical explanation for the complement fixation reaction lead a number of authorities 

 to the belief that the positive Bordet-Gengou reaction was in reality no amboceptor ac- 

 tion, but a result of a similar precipitation process. Wassermann and Bruck, Liefmann, 

 Wassermann and Citron, and later on Moreschi himself realized that this physical ex- 

 planation was incorrect, inasmuch as complement fixation took place even if all preci- 

 pitation was prevented by heat or other influences. Furthermore, complement binding 

 of an unspecific nature can be produced by the mixture of glycogen or peptone with 

 serum, a procedure wherein surely no precipitation plays any part. Finally Moreschi 

 showed that there were strongly precipitating sera which nevertheless did not exhibit the 

 Bordet-Gengou phenomenon. 



Thus was definitely established that the complement fixation was 

 entirely independent of either bacteriolysis or precipitation. 



Following Moreschi' s researches, Neisser and Sachs continued Gengou's 

 studies and advised this demonstration of the proteid amboceptors as a 

 control to the precipitation method for the differentiation of proteids. Its 

 action is so much finer, and more delicate than the precipitin test that even 

 the minutest traces of proteid can be recognized. 



With the encouraging results of Neisser and Sachs in mind, Wassermann 

 attempted by the use of highly immune antibacterial serum to discover any 

 soluble bacterial proteids which may exist in the blood, derived from the 

 respective bacteria invading the organism at the onset of an infection. 

 Practical application proved that not enough of these proteids existed free 

 in the circulation, but that they were probably bound by the tissue cells. 



Wassermann and Bruck then employed the complement fixation test 

 with the idea of demonstrating the existence of the respective antigens in the 

 diseased organs. Tuberculous glands and lungs served as material for 

 this experiment. They were able to obtain complement fixation when an 

 extract of tuberculous organs as antigens was mixed with a tuberculous 

 serum (manufactured by the Hochst Farbwerke). If instead of the lat- 

 ter, the serum from tuberculous individuals was substituted, no positive 

 complement fixation reaction was obtained. On the other hand, the 

 reaction was given if the human tuberculous serum employed 

 Antituber- came from an individual who had received therapeutic inocu- 

 culin. lations of tuberculin. In other words, the serum of treated 

 individuals contained, in contrast to the untreated ones, 

 amboceptors against a soluble tuberculous substance also present in the 



