SEROLOGICAL METHODS IN THE STUDY OF PROTOZOA 421 



The precipitin test is comparatively simple and easy to per- 

 form. As has been pointed out previously, the greatest obstacle 

 is the preparation of a satisfactory test antigen. Besides the 



TABLE 4 



PROTOCOL FOR THE COMPLEMENT FIXATION TEST 



(The dilutions here are in accordance with the preliminary tests of 

 Tables 2, 3, and 4) 



test antigen, antiserum, either from infected or immunized animals, 

 is required. If enough reagents are available, a protocol similar 

 to the one given in Table 6 for agglutination may be used, in which 

 either the amount of test antigen is held constant and the amount 



TABLE 5 



PROTOCOL FOR THE PRECIPITIN TEST ("rING" TEST) 



* To be layered carefully on the antiserum. 



of antiserum is varied, or the amount of antiserum is held con- 

 stant and the amount of test antigen varied. If the reagents are 

 at a premium, however, the "ring" test has proved efficient and 



