206 G. G. Heslop: 



conglutinin present in the test serum (bovine serum) reinforces 

 a small amount of complement, which has not been fixed, and 

 permits haemolysis of the sensitised red blood cells to occur. 



The variation in time required for this haemolysis to occur 

 in the test is due to the amount of complement and conglutinin 

 present and capable of acting in combination to bring about 

 haemolysis. 



The amount of conglutinin present in bovine sera differs 

 very considerably. It is on account of this variability in the 

 conglutinin content of the test sera that I prefer to titrate each 

 test serum separately, and thus arrive at the proper quantity of 

 -each to use in the final test. 



Titze and Gieze apparently do not do this, but adopt as a stan- 

 dard amount approximately 0.1 c.c. of a 1 in 10 dilution. This 

 latter method I have proved to be particularly prone to produce 

 reactions which are not as sharply defined as when the test serum 

 has been titrated, and the proper quantity, revealed by the titra- 

 tion, employed in the final test. With certain sera, such as those 

 which give border line reactions, the proper titration of the test 

 -serum is an absolute essential to a reliable result in the final test, 

 for an amount of serum either short of, or in excess of the 

 proper quantity, would be sufficient to produce a totally different 

 result to the proper one. 



Experiments to Remove Conglutinin from Bovine 



Serum. 



The results of the complement fixation experiments outlined 

 in the previous chapter have proved that complement fixing anti- 

 bodies are present in the sera of animals affected with 

 contagious pleuro-pneumonia. It has also been demonstrated 

 that by adopting a special technique, it is possible to test a serum 

 for the presence or absence of these antibodies. 



The presence of conglutinin in bovine serum has made the 



elaboration of a special technique necessary for this test, which 



requires very careful manipulation in all stages, and very careful 



•observation in the final stage in order to guard against error in 



the final reading. 



If conglutinin could be eliminated altogether from the bovine 

 serum, it was thought that the test with sera deprived of con- 

 glutinin could be much simplified, and the necessity for careful 

 and exact observation of the time required for haemolysis to 

 'Occur in the final stage could be dispensed with. 



