AGGLUTININS . 919 



(a) In which series of tubes is agglutination most complete? 



(b) Discuss the question of specificity of the agglutinins. 



(c) How do you explain group agglutination? 



(d) Are group agglutinins present to the same degree as the main 

 agglutinin? How may the group agglutinins be eliminated? 



(e) Of what value is the agglutination reaction in showing the bio- 

 logic relationship of bacteria? 



(f) How would the agglutination reaction be used in the diagnosis 

 of an unknown microorganism? 



EXPERIMENT 58. PRO-AGGLUTINATION AGGLUTINOIDS 



1. This very important phase of agglutination may have been noted in the pre- 

 vious experiments, especially if old immune serums were used, when there is a possi- 

 bility that agglutinin has degenerated in agglutinoids. Agglutinoids having a stronger 

 affinity than agglutinin for the agglutinogen, and having lost the agglutinophore 

 group, produce little or no agglutination and prevent the action of agglutinin until 

 diluted out of action in the higher serum dilutions. In this way agglutination may be 

 poor or absent in low and present in higher dilutions, an important practical fact 

 to be remembered. 



2. The action of agglutinoids may be seen by conducting a macroscopic test with 

 an old immune serum. 



3. Otherwise some agglutinoid may be produced by heating an immune serum 

 to 60 C. for an hour on the water-bath and conducting the test with dilutions of the 

 heated serum. 



4. Repeat the tests with old and heated immune serums in dilutions of 1:40, 

 1:80, 1:160, 1:320, using the macroscopic and microscopic technic, as this phe- 

 nomenon of pro-agglutination is not infrequently found in the routine Widal reaction 

 in typhoid fever. 



EXPERIMENT 59. THE ABSORPTION OR SATURATION AGGLUTINATION 

 REACTION (CASTELLANI) 



1. Immunize a rabbit with three intravenous injections of a heated emulsion of 

 Bacillus typhosus and three of Bacillus paratyphosus "B" or Bacillus coli, according 

 to the technic given under Active Immunization and Methods of Animal Inoculation. 



2. With this immune serum conduct a test according to the technic given in the 

 text. 



(a) Of what practical value is this method? 



(b) What are "major" and "minor" agglutinins? 



EXERCISE 23. AGGLUTININS (Continued) 

 EXPERIMENT 60. HEMAGGLUTININS 



1. Secure 0.1 c.c. of antihuman hemolysin prepared by giving a rabbit a series 

 of injections of washed human erythrocytes. Inactivate the serum by heating to 

 55 C. for half an hour. Dilute 1 : 100 by adding 9.9 c.c. salt solution. 



2. Prepare 10 c.c. of a 1 per cent, suspension of washed human erythrocytes. 



