i88 THE PRINCIPLES OF IMMUNOLOGY 



and Meier showed that alcoholic extracts of normal or syphilitic fetal 

 organs operate equally as well as the watery extracts of syphilitic or- 

 gans. These studies demonstrated that the antigen in the Wassermann 

 test is not necessarily derived from the .treponema pallidum, is alcohol 

 soluble and therefore is largely of lipoidal nature. Landsteiner, Muller 

 and Potzl extracted I. gram heart with 50. c.c. absolute alcohol but 

 this method has been somewhat modified. For practical purposes 50 c.c. 

 absolute alcohol are placed in a wide-mouth amber bottle and as 

 guinea-pigs are killed in the laboratory the heart is freed from blood 

 and connective tissue, cut into a few pieces and placed in the alcohol. 

 When ten hearts are so collected they are dried and ground in a mortar. 

 Ten grams of the dried powder are returned to the alcohol and the 

 volume made up to 100. c.c. This is shaken for twelve hours and placed 

 either at 60 C. for about twelve hours or at 37 C. for about five days. 

 It is then filtered and the filtrate preserved in a cool, dark place. Further, 

 a second extraction with alcohol of the first dried extract yields an 

 antigen of greater value because it contains less lytic and anti-lytic 

 substance, although it may be slightly weaker in fixing power. Appar- 

 ently, however, the alcoholic extracts of syphilitic organs produce more 

 specific antigens. To prepare such an antigen 100 grams syphilitic 

 liver are freed from surrounding tissue, washed free of blood and cut 

 into fine pieces- This is extracted in 1000 c.c. absolute alcohol for a 

 week at 37 C., the flask being shaken several times daily. It is 

 then filtered and titrated. 



Porges and Meier found that lecithin could, within certain limits, 

 be substituted for the antigenic extracts. This naturally led to extensive 

 investigation of the nature of the substance or substances concerned. 

 The fact that ether extracts of alcohol soluble antigen, according to 

 Levaditi and Yamanouchi, did not contain antigen led to the thought 

 that salts of bile acids might serve as antigens. Neither lecithin nor 

 salts of bile acids give consistent results in the actual test and at the 

 present time no pure substance serves well as antigen. The importance 

 of lecithin was further emphasized by the refined technic of Noguchi 

 in preparing the so-called acetone insoluble antigen. This method ap- 

 pears to be especially adapted to the use of normal human organs, 

 particularly heart. The tissue is cut into fine pieces^jnixed with five 

 times its weight of absolute alcohol and placed at '37 C. for from 

 five to seven days. It is then filtered and the clear filtrate evaporated 

 in a dish by means of an electric fan or in a vacuum desiccator. The 

 residue is taken up in as small a volume of ether as will permit solution 

 and allowed to stand overnight. The clear supernatant fluid is decanted 

 and slightly evaporated. To it is added four volumes of acetone. The 

 supernatant fluid is poured off and the precipitate allowed to evaporate 

 to a resinous consistence. Three-tenths of a gram of this mass is 

 added to a mixture of i.o c.c. ether and 9.0 c.c. pure absolute methyl 

 alcohol and preserved in a dark, cool place. According to certain re- 

 ports, it would appear that this antigen gives positive results in cases 

 which are negative with other antigens and in which syphilis has not 



