COMMUNICABLE DISEASES. 219 



that display a marked affinity for lipoids and in particular, lecithin. Many 

 workers now use, as antigen, an emulsion of lecithin or guinea-pig heart, 

 in place of the watery emulsion of the liver obtained from a syphilitic fetus 

 as described by the originators of the reaction; the advantages being that 

 lecithin and guinea-pig's heart are always on hand and alcoholic extracts are 

 more stable than watery extracts. 



The following is an outline of the method of procedure as given by 

 George Gillman of San Francisco. 



i. Antigen (a) (original Wassermann); the liver of a syphilitic fetus is 

 cut into very small pieces and an emulsion made of it by shaking with normal 

 salt solution (0.85 per cent.) in the proportion of one (i) part of the liver to 

 live (5) parts of the salt solution. After the shaking is completed, the 

 supernatant liquid is removed and clarified by centrifugalization, after 

 which the clear liquid is pipetted off, one-half of i per cent, of phenol 

 added and stored on ice until wanted for use. 



(b) If lecithin is to be used as the antigen, it is prepared as follows: Make 

 up a solution of pure lecithin in alcohol ; of this alcoholic solution, a quantity 

 equal to o.i gm. of lecithin, is added to 100 c.c. of normal salt solution. This 

 is also stored on ice. 



(c) Guinea-pig heart extract is prepared as follows: The heart is 

 rubbed up very fine in a mortar (containing ground glass) with absolute 

 alcohol in the proportion of one (i) gram of the heart to 25 c.c. of absolute 

 alcohol. It is then heated to 60 C. for an hour, filtered through filter-paper 

 and kept in the refrigerator ready for use. 



As the strength of the antigen will vary in different preparations, it 

 must be standardized before being used. It should be of such strength 

 that the quantity used will not hemolyze i.o c.c. of a 5 per cent, suspension 

 of washed lamb's blood-corpuscles in the presence of 0.2 c.c. of a known 

 positive serum, o.i c.c. of complement, and 2 minimal units of the hemolytic 

 serum. The unit is determined as follows : A series of test-tubes are prepared 

 each containing the same quantities of the reagents mentioned above and 

 varying amounts of the antigen. The usual technic is followed and the 

 unit determined by the quantity of antigen that inhibited hemolysis. After 

 this determination the same antigen must be tested with a known negative 

 serum used in place of the positive serum and using double the unit of antigen. 

 This double unit should not inhibit hemolysis of the blood cells. The unit 

 being determined, the antigen is so diluted that i.o c.c. will contain 

 the unit. 



2. Antibody. The blood serum or cerebrospinal fluid of the syphilitic 

 person. A sufficient quantity of the patient's blood is collected from the 

 lobe of the ear or finger tip, in any sterile vial (best in a Wright's capsule), 

 aseptic precautions, of course, being observed. The blood is then 



