PRACTICAL APPLICATIONS OF METHOD 



Table Compiled by Boas, loc. cit., p. 138. 





the milk of a syphilitic mother. Serum obtained at autopsy is not 

 suitable for the reaction, since this, for unknown reasons, may often 

 give a positive reaction in non-syphilitic cases. 



COMPLEMENT OR ALEXIN FIXATION AS A METHOD OF 



DETERMINING THE NATURE OF UNKNOWN 



PROTEIN 



FOKENSIC ALEXIS FIXATION TESTS 



Our preliminary discussions of the principles underlying alexin 

 or complement fixation have revealed that alexin is bound not only 

 by sensitized cells but also by the specific precipitates formed when 

 an unformed protein antigen is mixed with its specific antiserum. 

 This discovery, made by Gengou, was attributed by him, it will be 

 remembered, to the presence of "albuminolysins," or protein sensi- 

 tizers, antibodies which have been by many observers regarded as 

 separate from the precipitins, but which we believe, for stated rea- 

 sons (see p. 193), to be very probably identical with the precipitating 

 antibodies or precipitins. However this may be, when a dissolved 

 antigen is mixed with its antiserum alexin fixation is exerted by the 



