932 EXPERIMENTAL INFECTION AND IMMUNITY 



(a) Examine tubes and record your results. 



(b) Why was the serum control on each serum necessary? 



(c) Why was the hemolytic system control necessary? 



(d) Why was the antigen control necessary? 



(e) What is meant by non-specific complement fixation? 



(f) What is meant by specific complement fixation? Explain the 

 phenomenon. Which tube of this series shows specific complement fixa- 

 tion and why? Is there any evidence of non-specific fixation in any of 

 the tubes? If so, what bearing would this x have on the results of this 

 test? 



(g) What is meant by complement deviation? 



(h) Upon what does the specificity of complement fixation depend? 



EXERCISE 34. ANTIGENS FOR THE WASSERMANN REACTIONS 



EXPERIMENT 86. PREPARATION OF ANTIGENS FOR THE WASSERMANN 

 REACTION 



1. Prepare 50 c.c. of an alcoholic extract of syphilitic liver (see page 444). 



2. Prepare an extract of acetone-insoluble lipoids from 20 grams of beef heart 

 (see page 446). 



3. Prepare 50 c.c. of a cholesterinized alcoholic extract of human heart (see 

 page 421). 



(a) Are antigens for the Wassermann syphilis reaction specific? 



(b) Upon what does the high specificity of the Wassermann reac- 

 tion depend? 



(c) What constitutes a specific antigen for the Wassermann reac- 

 tion? 



(d) Discuss the important relation of antigen to the Wassermann re- 

 action. 



EXERCISE 35. ANTIGENS (Continued) 

 EXPERIMENT 87. METHODS OF TITRATION OF ANTIGENS 



While the above extracts are in the course of preparation, stock ex- 

 tracts may be used for titration. After the student has finished the 

 above three extracts, they are titrated in a similar manner. 



1. Dilute 1 c.c. of an alcoholic extract of syphilitic liver in a test-tube 1:10 by 

 slowly adding 9 c.c. of normal saline solution. Dilute a cholesterinized extract (1 : 20) 

 by slowly adding 9.5 c.c. salt solution to 0.5 c.c. of extract. 



2. Conduct the anticomplementary titration of each (page 452). 



3. Conduct the antigenic titration of each (page 455). 



(a) What is meant by the anticomplementary dose of an antigen? 



(b) What is meant by the antigenic dose of antigen? 



