MODIFICATIONS OF THE WASSERMANN REACTION 455 



genie unit ( = 0.02 c.c. undiluted antigen); five times this amount equals 

 0.1 c.c. of the first emulsion (1:10), which is the amount to be used in 

 making the main tests. 



Unless the antigen shows signs of deterioration, these titrations need 

 be made only about once a month. 



If paper antigen is employed, both titrations are conducted in 

 exactly the same manner by adding increasing lengths of a strip of 

 dried paper 5 mm. in width, impregnated with the antigen. 



5. Fluid to be Tested. If active serum is used, it should be fresh, 

 free from hemoglobin, and preferably not over twenty-four hours old. 

 The dose is 0.02 c.c., or one capillary drop; inactivated serums are used 

 in doses of 0.08 c.c., or four capillary drops. Cerebrospinal fluid is used 

 unheated in doses of 0.2 c.c., or 10 capillary drops. Sufficient blood 

 for this test may be collected in a Wright capsule. (See p. 32.) 



6. The Test. The complement, amboceptor, antigen, and serums 

 may be conveniently measured by drops from a capillary pipet (Fig. 

 2). In placing a drop the pipet should be held uniformly at an angle 

 of 45 degrees, or else the size of the drop will differ, depending on whether 

 the pipet is held vertically or horizontally. 



Arrange four pairs of small test-tubes (10 by 1 cm.) in a rack con- 

 taining two rows cf holes. Into each of the tubes on the front row 

 place five drops (0.1 c.c.) of antigen emulsion (alcoholic solution, 1 part, 

 with saline solution, 9 parts); then add five drops (0.1 c.c.) of com- 

 plement (40 per cent.) to all the tubes. Into each of the first pair of 

 tubes place one drop (0.02 c.c.) of active or four drops (0.08 c.c.) of 

 inactivated patient's serum, and mark the front tube with the patient's 

 name. To each of the second pair of tubes add an equal amount of 

 syphilitic serum known to give a positive reaction (positive control), and 

 to each of the third pair add normal serum known to give a negative re- 

 action (negative control). Mark the tubes in the front row of each pair 

 respectively. The front tube of the fourth pair is the antigen control, 

 and the rear tube the hemolytic control, and each should be so labeled. 

 Into each tube place 1 c.c. of the 1 per cent, corpuscle suspension and 1 

 c.c. of saline solution, making the total volume in each tube about 2 c.c. 

 Shake each tube and incubate at 37 C. for one hour (half an hour in the 

 water-bath). At the end of this time add two units of amboceptor to 

 each tube, shake gently, and reincubate for two hours (one hour in the 

 water-bath). During this time the tubes should be shaken gently 

 once or twice to break up any masses of agglutinated corpuscles. 



The following chart, after Noguchi, illustrates the various steps to 



