466 



MICROBIOLOGY 



and in this case in order to get the best results the serum 

 should be inactivated before using. Serum preserved in this 

 'way can be kept in the ice box for from three months to a 

 year. It must, however, be titrated at intervals of a few weeks 

 as the titre may change. 



Titration of Hemolytic Rabbit Serum. Dilutions of the 

 hemolytic serum are made in eight test tubes, according to the 

 following table. It is best to use pipettes to measure the re- 

 quired amounts. 



TABLE NO. I. 



DILUTIONS OF HBMOLYTIC AMBOCEPTOR (RABBIT SERUM). 



The titration proper is then made in the following man- 

 ner: Eight additicnal test tubes are each filled with 2.5 cc. of 

 salt solution to which is then added the hemolytic serum 

 (amboceptor) in quantities of 1 cc. of the different dilutions 

 (Table No. I) to each tube. Afterwards the complement of 

 the guinea pig serum is added in quantities of 0.5 cc. of a 

 10% dilution to each tube, and finally 1 cc. of a five per cent 

 suspension of washed sheep corpuscles in salt solution is placed 

 in each tube. 



Besides these eight tubes there are also three control tubes, 



