11 



Twelve days after the last Injection each rabbit was 

 anesthetized with ether and by the use of a sterile 

 syringe and needle about forty cubic centimeters of blood 

 were aspirated from the heart. The blood was placed in 

 sterile glass tubes, which were then placed in the ice- 

 box until the serum separated from the clot. The clear 

 serum was then pipetted off into sterile tubes and an 

 equal amount of glycerol was added for preservative. 



Each of the above antisera was then tested against 

 the three different antigens. The tests used were as 

 follows: 



a. Complement fixation 



b. Agglutination 



c. Precipitin 



d. Anaphylaxis 



a. The complement fixation test. In testing the 

 antigens and antibodies by the method of fixation of 

 complement, guinea-pig serum diluted with ten parts of 

 physiological saline was used for complement. The anti- 

 human-rabbit hemolytic system was used; i.e., the blood 

 serum of rabbits which were immunized against human red 

 blood corpuscles was used as hemolytic antibody. The 

 following table sets forth the procedure for obtaining 

 the hemolytic antibody: 



Table #4. Rabbit injected with hemolytic antigen. 



The animal was bled and the serum was obtained and 

 preserved in a manner similar to that previously des- 

 cribed. The hemolytic system was titrated as follows: 

 the antigens consisted of a five per cent suspension of 

 washed blood cells; the complement was guinea pig serum 

 diluted with ten parts of salt solution. The hemolytic 

 antibody was then diluted with twenty parts of salt 

 solution and titrated according to the following table: 



