THE TECHNIQUE OF SERUM REACTIONS 263 



trifugalizing them from salt solution suspensions and adding to about 

 20 mgms., 90 mgms. of common salt, rubbing up with a glass rod for 

 an hour, and then adding distilled water to isotonicity. This is the 

 method of Besredka. This method has been used with success by 

 Miller and Zinsser in the case of tubercle bacilli for complement-fixation 

 in tuberculosis. 



Wassermann and Brack 1 prepare bacterial antigen by emulsifying 

 growths of about ten agar slant cultures in 10 c.c. of sterile, distilled 

 water. This is shaken for twenty-four hours in a shaking apparatus. 

 At the end of this time 0.5 per cent of carbolic acid is added and the 

 fluid cleared by centrifugalization. 



The Wassermann Test for the Diagnosis of Syphilis. 2 The sub- 

 c tnnces for the test are the following: 



I. The Antigen. In their original experiments, Wassermann and 

 ! is collaborators made use of salt-solution extracts of the organs (chiefly 

 of the spleen) of a syphilitic fetus. The tissue was cut into small pieces 

 and to one part by weight of this substance, four parts of normal salt 

 solution and 0.5 per cent of carbolic acid were added. This was shaken 

 in a shaking apparatus for twenty-four hours, and after this the coarser 

 particles removed by centrifugalization. The reddish supernatant 

 fluid was used as the antigen and could be preserved for a long time in 

 dark bottles in the ice chest. 



Alcoholic extracts of syphilitic organs were subsequently used by a 

 number of authors, syphilitic liver being extracted for twenty-four 

 hours with five times the volume of absolute alcohol. This was filtered 

 through paper and the alcohol evaporated in vacuo at a temperature 

 not above 40 C. About 1 gram of this material was then emulsified 

 in 100 c.c. of salt solution to which 0.5 per cent of carbolic acid has 

 been added. 



It was soon found that the Wassermann antigen was a purely non- 

 specific substance, and since this discovery was made there are few 

 laboratories in which syphilitic organs are at all used. It appears that 

 lipoidal extracts from almost any tissue can be employed, and that 

 fairly useful antigens can even be obtained with solutions of commer- 

 cial lecithin and mixtures of commercial lecithin and sodium oleate. It 

 is apparent, therefore, that in the Wassermann reaction an even sus- 



1 Wassermann und Bruck, Med. Klinik, 55, 1905, and Deut. med. Woch., xii, 1906. 



2 Wassermann, Neisser und Briick, Deut. med. Woch., xix, 1906; Wassermann, 

 Neisser, Bruck und Schucht, Zeit. f. Hyg., Iv, 1906. 



