566 THE KELATION OF COLLOIDS AND LIPOIDS TO IMMUNITY 



it is to be used it should be dilated with water in such amount that 1 c.c. 

 will contain the largest amount that does not cause a marked reduction 

 of surface tension in normal serum. As a rule, this dilution is between 

 1 : 50 and 1 : 100 (Kohler and Luger) 1 . 



3. A syphilis antigen may be prepared by extracting 0.5 gram of 

 dried and powdered syphilitic liver with 50 c.c. of absolute alcohol for 

 two hours at 37 C. with frequent shaking. Filter, and concentrate to 

 10 c.c. 



4. A bacterial antigen, as e. g., one of typhoid bacilli, may be prepared 

 as follows : Wash off five forty-eight-hour agar cultures of typhoid bacilli 

 with 5 c.c. of normal salt solution for each tube. Cover the emulsion 

 with toluol, and shake vigorously for several hours. Place in an in- 

 cubator at 37 C f for forty-eight hours, and filter through a sterile 

 Berkefeld filter. This filtrate may be used as antigen, or it may be 

 used in preparing an alcoholic extract in the following manner: To the 

 original aqueous filtrate add 50 c.c. of absolute alcohol. Allow the 

 mixture to stand for one-half hour, shake, centrifugate, and then mix 

 the sediment with 20 c.c. of absolute alcohol. Shake thoroughly once 

 more, and again centrifugate. Combine the two extracts, and con- 

 centrate on the water-bath to about 20 c.c. 



Practical Value. This test is quite delicate, and errors due to faulty 

 technic are quite likely to creep in. Unless all precautions are rigidly 

 observed, the results are worthless. Although an extensive literature 

 has accumulated bearing evidence as to the value of the test as a diag- 

 nostic procedure, the method has not, however, come into general use. 



Ascoli and Izar especially have advocated the test in the diagnosis of 

 cancer. In 100 cases of malignant tumors, they obtained 93 positive 

 reactions; in 103 cases of other diseases they obtained only one positive 

 reaction. Tedesko, Stabilini, Leitch, Kelling, and others have reported 

 favorably upon the practical value of the test in the diagnosis of cancer. 

 Burmeister 2 has found that a negative reaction has some value in 

 excluding cancer, and is of more value in arriving at a diagnosis than a 

 positive reaction, i. e. } it has a higher negative than a positive value. 



The test has also been used in the diagnosis of typhoid fever, para- 

 typhoid fever, syphilis, tuberculosis (positive only in active cases) 

 echinococcus disease, etc. Obviously, other methods of diagnosis, such 

 as the agglutination reaction and the Wassermann reaction, have super- 

 seded this test in practical diagnosis. The method possesses, however, 

 considerable theoretic interest and is worthy of further investigation. 



1 Wien. klin. Wochenschr., 1912, 25, 1114. 2 Jour. Infect. Dis., 1913, 12, 459. 



