236 CHEMISTRY OF THE IMMUNITY REACTIONS 



different liver extracts varies nearly directly with its power to com- 

 bine with iodin - (Noguchi and Bronfenbrenner) , which indicates 

 that the unsaturated fatty acids are important in the reaction.^ 

 Lecitliins from different sources vary in efficiency, heart lecithin being 

 jnore active than liver lecithin, brain and egg yolk lecithin following. 

 Addition of cholesterol to the lecithin solutions increases greatly their 

 activity.* An acetone-precipitated "antigen" of this class is not a 

 true antigen, however, for fixation antibodies are not developed in 

 aninuils injected witli such a lipoid which has been shown to be en- 

 tirely efficient in the Wassermann reaction.'^ 



As for the substance in the syphilitic serum which participates in 

 the Wassermann reaction, it w-ould seem to be related to the globulins, 

 which are decidedly increased in the blood and spinal fluid '^ of 

 sypliilitics,'''^ especially the euglobulin.' P. Schmidt ^ ascribes the 

 reaction to the physico-chemical properties of the globulins of the 

 syphilitic serum, which, he believes, possess a greater affinity for the 

 colloids of the antigen than normal globulins; this affinity is held in 

 check in normal serum b}' the albumins of the serum, which are rela- 

 tively or absolutely decreased. That physico-chemical factors do play 

 a part is evidenced by the common observation that the turbidity of 

 the antigen suspension is closely related to its efficiency, clear solu- 

 tions being less active. Slight changes in H-ion concentration will 

 change a reaction from negative to positive, or reverse; and neutral 

 salts can change a negative to a positive reaction, but not the reverse 

 (Gumming).'*'^ The lipoids in syphilitic sera are said by Peritz ^ to be 

 increased, but the lipoid content and the antibody titer do not show 

 any constant relation (Bauer and Skutezky ).■'-'' The cholesterol con- 

 tent of syphilitic blood shows no evidence of a quantitative relation to 

 the Wassermann reaction.'*'' Friedemann ^° believes that a globulin- 



2 Not corroborated by Browning, Cniioksliank and Gilmour. 



3 An interesting obsorvation made by Xognclii and Bronfenbrenner. is that ex- 

 tracts frona fatty livers arc almost devoid of antigenic properties; but So (Cent. f. 

 Bakt., 1912 (63), 438) found that the extract from fatty hearts of guinea-pigs 

 was more active than from normal hearts. 



4 Browning et al., Zeit. Immunitiit., 1012 (14). 284; Jour. Pathol, and Bact., 

 1911 (16), 135 and 225. Klein and Fraenkel believe the "antigen" of ox heart 

 extracts to be a comltination of lecithin with cliolosterol and small amounts of 

 a soap-like substance similar to jecorin (IMiincli. mcd. \Voch., 1914 (61), 651). 



5 Fitzgerald and LeaOics. Tniv. of Calif. I'ul)!., Path., 1912 (2), 39. 

 ePfein'er, Kol)cr aiid Field, Broc. Soc. Exp. Biol., 1915 (12), 153. 

 oaSee Kowe, Arch. Int. ^Nled., 1916 (18), 455. 



TMiiller and Hough, Wien. klin. Woch., 1911 (24), 167. 



8 Zeit. f. Hvg., 1911 (69), 513. See also Hirschfeld and Klinger, Zeit. Immuni- 

 tUt., 1914 (2i), 40. 



8a Jour. Infect. Dis., 1916 (18), 151. 



Zeit. exp. Path., 1910 (8), 255. 



'JaWicn. klin. Wodi., 1913 (26), 830. 



«b Weston, Jour. Med. Pes., 1914 (30), 377; Stein, Zeit. exp. Med., 1914 (3), 

 309. 



10 Zeit. f. Ilvg., 1910 (67), 279. 



