262 INFECTION AND IMMUNITY 



is used; and vice versa, by the use of a known antibody a suspected 

 antigen may be determined. 



When testing immune sera for amboceptors given rise to in man or 

 animals by microorganisms which can be cultivated, either the whole 

 bacteria or extracts of the bacteria may be used as an antigen. 



For the diagnosis of syphilis by this method, in the so-called " Wasser- 

 mann reaction," the antigen employed was originally obtained by the 

 extraction of syphilitic organs, in which free syphilitic antigens, i.e., 

 uncombined products of Spirochsete pallida, were assumed to be present. 

 As this reaction has recently become prominent and has proven of no 

 inconsiderable diagnostic value, the technique given below for immune- 

 body determination by complement fixation will be that utilized in 

 the Wassermann test for sj'philis. 



The reader will, however, bear in mind that the test may be 

 applied to other diseases simply by the substitution of the suitable, 

 specific antigen. Thus, when cultivatable bacteria are used as antigens, 

 Bordet and Gengou make use of a thick salt-solution emulsion of a 

 twenty-four-hour agar-slant culture of the microorganisms. In the 

 case of the tubercle bacilli, these authors emulsify 80 milligrams of 

 the bacilli in I c.c. of the salt solution. Wassermann and Bruck,' on 

 the other hand, prepare their bacterial antigen in the following way: 

 The growths of about ten agar slant cultures are emulsified in 10 c.c. 

 of sterile, distilled water. This emulsion 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. These 

 antigens become slightly weaker during the first ten or fourteen days, 

 but after that remain fairly constant. For the determination of tuber- 

 culosis antibody, these authors make use of either old tuberculin 

 or the new tuberculins "TR" or "Bazillen Emulsion." 



The Wassermann Test for the Diagnosis of Syphilis.^ — The sub- 

 stances for the test are the following: 



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

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

 of the spleen) of a syphilitic fetus. The tissue substance was cut in- 

 to 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 



' Wassermann und Bruclc, Med. Klinik, 55, 1905, and Deut. med. Woch., jdi, 

 1906. 



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

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



