WASSERMANN TESTS 153 



as i mm., 2 mm., 3 mm., 5 mm., and so on. The narrowest strip which gives hasmo- 

 lysis in one hour equals one unit. Thus if a piece 5 mm. wide was required to pro- 

 duce haemolysis, 5 mm. of the paper would have a value of one unit. 



NOGUCHI'S METHOD. 



For the suspension of red cells use a 1/2% suspension of washed 

 human red cells. 



For complement use fresh guinea-pig serum in a dilution of i part 

 to i 1/2 parts of salt solution (40%). 



Experiment. 'Take 4 small test-tubes (12 by 125 mm.) label id, ib 

 and 20, 2b, respectively. Into la and ib each put i drop of the serum 

 of the patient to be tested and into ia and 2b each put i drop of the 

 serum of a person known to give a positive test for syphilis. Next 

 add to each of all four tubes i c.c. of the 1/2% suspension of washed 

 red cells. Then add to each tube o.i c.c. of the 40% fresh guinea-pig 

 serum. Now add to tube la and tube ia each o.i c.c. of the i to 10 

 antigen dilution (opalescent working antigen emulsion). Tubes ib and 

 2b are controls not containing antigen. Mix contents of tubes thor- 

 oughly and incubate at 37 C. for one hour or for 1/2 hour in a water 

 bath. Now add to each of the four tubes 2 units of the immune 

 haemolytic serum, as measured off on the amboceptor paper strip thus 

 with a paper of which 2 mm. equals i unit, drop into each tube 4 mm. 

 of the strip. 



The tubes without antigen (ib and 26) should show good haemolysis. 

 Tube 20, that of the known syphilitic, with antigen, should not show 

 haemolysis and that of the person examined (10) should show haemolysis 

 in case the test is negative for syphilis. Moderately positive cases may 

 show a slight trace of haemolysis. In case the tubes without antigen are 

 negative (no haemolysis), repeat the test with smaller amounts of human 

 serum. It may be advisable to employ the serum of a person known to 

 be free from syphilis. In this case we should use two additional tubes, 

 30 and 3#, conducting the test as for the syphilitic control serum. 



Many workers prefer to use inactivated serum for the test. In this case we should 

 add four times as much of the inactivated serum as for the unheated serum. 



Inactivation not only destroys complement but likewise diminishes the strength 

 of the antibody content of the serum. Factors such as character of food and general 

 condition influence the complement strength of guinea-pig serum so that it is ad- 

 visable to titrate the guinea-pig serum. To do this take i c.c. of a i% emulsion of 

 human red cells and drop in one unit of amboceptor paper. The amount of comple- 



