204 INFECTION AND RESISTANCE 



From these results also we may infer that the Wassermann reac- 

 tion does not represent a fixation of alexin by the union of a specific 

 syphilitic antigen with antibodies found against the Spirochceta pal- 

 lida. Noguchi concludes that it is caused by "lipotropic" substances 

 in the sera of syphilitic human beings ; a conclusion which is justi- 

 fied by the fact that the antigens used, all of them, contain large 

 quantities of lipoids. It must be acknowledged, however, that we 

 have no definite information concerning the nature of the reaction 

 beyond this. Schmidt 22 believes that it is a colloidal reaction, and 

 depends upon the union of the serum globulins with the extract 

 colloids in the antigen. In normal serum such a union is prevented 

 by the albumins which act as a sort of protective colloid. In syph- 

 ilitic serum the globulins are increased quantitatively or are changed 

 qualitatively in the degree of their dispersion, or possibly in both 

 characteristics. He regards the serum globulins in the Wassermann 

 reaction as directly uniting with the extract colloid. 



Levaditi and Yamanouchi 23 also conclude that the Wassermann 

 reaction depends upon the union of two colloidal substances one a 

 non-proteid constituent of syphilitic serum (cholesterin derivatives 

 or fatty acids), the other the lipoidal constituents of the antigen. 

 Like others they found that the active substances in the antigenic 

 extracts are non-protein and alcohol soluble. 



It is interesting to note, moreover, that Forges and Meier 24 ob- 

 served actual precipitation when syphilitic serum was added to 

 lecithin emulsions. In consequence, attempts have been made to 

 make the diagnosis of syphilis by direct precipitation of syphilitic 

 serum by such emulsions of lecithin and of sodium glycocholate 

 (Merck). The results of these investigations as well as those of 

 Klausner, 25 who claims that syphilitic sera are more easily precipi- 

 tated by distilled water than are normal sera, have led to no diag- 

 nostically reliable results, but they have seemed to show that the 

 serum globulins are probably more plentiful and more easily pre- 

 cipitated out of syphilitic than out of normal sera. 



The inference of many workers, therefore, has been that the 

 Wassermann reaction is primarily due to the precipitation of (prob- 

 ably) globulin by the lipoidal colloids of the antigen, the resulting 

 precipitate being capable of absorbing alexin. Jacobsthal 26 has ex- 

 amined mixtures of syphilitic serum and antigen by the ultramicro- 

 scopic method, and claims that precipitates are always present even 

 when they are not macroscopically visible. Bergel, 26 who has re- 



22 Schmidt. Zeitschr. f. Hyg., Vol. 69, 1911. 



23 Levaditi and Yamanouchi. C. R. de la Soc. de BioL, 1907, Vol. 63, p. 

 740. 



24 Forges and Meier. Berl kl. Woch., No. 15, 1908. 



25 Klausner. Wien. kl Woch., No. 7, 1908. 



26 Jacobsthal. Munch, med. Woch., 1910. 



27 Bergel. Zeitschr. /. Imm., Vol. 17, 1913. 



