860 PATHOGENIC MICROORGANISMS 



Investigations carried on in our own laboratory* in the last three 

 years have shown definitely, we think, that immunization of animals 

 with culture pallida produces antibodies, agglutinins, treponemacidal 

 substances, entirely analogous to similar substances produced against 

 bacteria. However, there is a biological change which takes place 

 when treponema pallidum is cultivated. The antibodies produced 

 with the culture pallida have no action whatsoever upon the virulent 

 organisms. The latter, indeed, seem to be entirely insulated against 

 such antibodies and do not induce antibody formation to any great 

 extent, in either the infected animal or man. Both active and 

 passive immunization with culture pallida and the sera produced 

 with them have no effect. We have obtained some evidence, how- 

 ever, that in rabbits a purely local resistance develops in the tissue 

 previously the site of a lesion. 



The occurrence of a Wassermann reaction was formerly supposed 

 to indicate the existence of specific syphilitic antibodies in the serum 

 of patients. More recent information regarding this reaction seems 

 to show that it depends upon the presence in the serum of syphilitic 

 patients of substances produced indirectly because of the presence 

 of syphilitic infection. It may be a relative increase of globulins 

 or, as Schmidt has suggested, a change in the physical state of the 

 globulins or other substances present in the serum. At any rate 

 it has been found that the fixation of complement in the Wasser- 

 mann reaction does not depend upon the occurrence of a specific 

 antigen-antibody reaction. In the first place the antigens most com- 

 monly used, and successfully so, in the Wassermann reactions, are 

 non-specific lipoidal extracts of normal organs. 



Again it has been demonstrated that extracts of cultures of the 

 Spirochaeta pallida as well as extractions from the testes of syphilitic 

 rabbits do not furnish an antigen suitable for the Wassermann 

 reaction. This has followed especially from the work of Noguchi, 35 

 of Craig and Nichols, 36 and ourselves. This forms a corollary to 

 the other experiments previously mentioned and shows that, what- 

 ever the Wassermann reaction may be, it is not a specific comple- 

 ment fixation in the sense of Bordet and Gengou. It must be 

 admitted, therefore, that our knowledge of syphilis immunity is in 



* Zinsser and Hopkins, Series of papers, Journ. Exp. Med., 1915 and 1916. 



85 Noguchi, Jour. Am. Med. Assoc., 1912. 



36 Craig and Nichols, Jour. Exp. Med., xvi, 1912. 



