134 THE BACTEKIOPHAGE 



knowledge of the nature of antitoxic immunity. One thing already 

 appears certain, namely, that the bacteriophage must play some 

 r61e in the manifestation of this immunity, since the antibacterio- 

 phagous serum sensitizes to the toxins. It is probable that this 

 sensitization of the animal must be associated with the inhibiting 

 power with which the antibacteriophage serum is endowed, an 

 action which we will shortly consider. 



ANTIBODIES TO THE BACTERIOPHAGOTJS ULTRAMICROBES 



Agglutinins 



It has been impossible to demonstrate definitely the presence 

 of agglutinins, although experimentation indicates that their 

 presence is probable. In all cases, if present, they are weakly 

 active. 



Experiment XLV. When a culture of the bacteriophage is centri- 

 fuged for 15 minutes at 3000 revolutions per minute no trace of sediment 

 appears; it requires a speed of at least 12,000 revolutions to obtain an 

 appreciable amount . A culture of the bacteriophage is mixed with one-tenth 

 of its volume of antibacteriophage serum and centrifuged for ten minutes 

 at 3000 revolutions. Counts of the ultramicrobes in the sediment and in 

 the supernatant fluid (after energetic shaking of the latter for five minutes) 

 shows that there are about three times as many germs in the sediment as 

 in the supernatant fluid. 



Is this agglutination? It is possible, but not certain. The 

 experiment is not sufficiently clear-cut to permit an affirmative 

 answer. The formation of agglutinins in the serum of treated 

 animals is subject to great variation, dependent upon the bac- 

 terial species injected. With Vibrio cholerae and with B. typhosus 

 for example, potent agglutinins are secured; with certain coli- 

 form bacilli and with B. Friedldnder they are usually so weak that 

 their action is almost inappreciable. We know nothing regard- 

 ing the formation of agglutinins in the case of the pathogenic 

 ultramicrobes. 



Amboceptors 



The test for an amboceptor specific for the anti-dysenteric 

 bacteriophage, detectable by the complement fixation reaction 



