422 



RESEARCH IN PROTOZOOLOGY 



consists in carefully layering about o.i of a cubic centimeter of the 

 lighter fluid (generally the test antigen) onto a like amount of 

 the heavier fluid (generally the antiserum) in small 5 by 50 milli- 

 meter tubes. A positive test shows a cloudy white precipitate of 

 varying thickness, according to the potency of the reaction, at the 

 interphase of the two liquids. The protocol in Table 5 has been 

 used in various malarial and helminthological studies. (Further 

 dilutions may be added if desired.) 



SEROLOGICAL REACTIONS WITH SUSPENSIONS OF THE PROTOZOA : 

 AGGLUTINATION, LYSIS AND PHAGOCYTOSIS 



A. Preparation of antigens. The test antigen for these tests 

 depends upon a homogeneous suspension (generally in saline, 

 sometimes in distilled water) of thoroughly washed organisms, 



TABLE 6 

 PROTOCOL FOR AGGLUTINATION TEST 



Mix and incubate i hr. at 27° C. ; refrigerate 12 hrs. ; examine the tubes 

 macroscopically or with a hand lens. 



either dead or alive. The need of a carefully standardized suspen- 

 sion of organisms, especially in the agglutination test, is apparent 

 when it is realized that any preliminary clumping or aggregation 

 will invalidate the end result. 



B. Materials required. The agglutination reaction has been used 

 to ascertain (i) whether an animal is infected with a certain 

 organism or (2) whether an organism under examination is iden- 

 tical with one used in obtaining a particular agglutination serum. 

 In the first case, varying dilutions of serum from the experimental 



