MODIFICATIONS OF THE WASSERMANN REACTION 449 



At the end of an hour 1 c.c. of sensitized corpuscles is added to all 

 the tubes. These are then gently shaken and reincubated for an 

 hour and a half, after which time the results are read. A final 

 reading made after the tubes have been allowed to stand overnight, 

 usually tallies very closely with this reading. 



Reading the Results. The controls are first inspected. The 

 corpuscle control should show no hemolysis, and the hemolytic control 

 be just hemolyzed. In series A of the antigen controls it is usually 

 found that in the first tube hemolysis is incomplete, whereas the 

 second and third tubes show complete hemolysis, indicating that the 

 antigen alone fixed a unit or one hemolytic dose of complement. The 

 last three tubes of series B are the serum control tubes, and the first 

 tube usually shows incomplete hemolysis, its degree depending upon 

 the age of the serum. Occasionally the second tube is also incom- 

 pletely hemolyzed, indicating that about two units of complement 

 have been absorbed. Unless the serum is quite anticomplementary, 

 the third tube is completely hemolyzed. 



The first nine tubes of series B are now examined. Browning and 

 Mackenzie have made an arbitrary rule to regard the reaction as 

 positive when lysis is incomplete with five hemolytic doses of com- 

 plement, in addition to the sum of the amounts inhibited by serum 

 and by antigen alone. When an alcoholic extract of syphilitic liver 

 is used as antigen, I have found this rule to be too lax, and I regard 

 the reaction as slightly positive when lysis is incomplete with two or 

 three doses of complement, in addition to the sum of the amounts inhib- 

 ited by serum and by antigen .alone. For example, if a given serum 

 and antigen each show fixation of but one dose of complement, and 

 hemolysis is slight or entirely inhibited in the second tube of the se- 

 ries B containing serum and antigen with four doses of complement, 

 the reaction is usually weakly positive. More strongly reacting 

 serums will absorb from six to ten doses of complement, and not in- 

 frequently the serum of an active case of syphilis will fix more than 

 20 hemolytic doses of complement (see Fig. 114). 



MODIFICATIONS OF THE WASSERMANN REACTION 



MODIFICATION OF NOGUCHI 



Among the large number of modifications of the original syphilis 

 leaction that have been devised, that of Noguchi has proved of dis- 

 tinct value. In this method an antihuman hemolytic system is 

 29 



