256 THE BACTERIOPHAGE 



they have disappeared. Experiment further shows that the 

 ultramicrobes pass quickly into the intestine. They can be 

 isolated from the intestine within about twelve hours after the 

 injection and they persist there for a somewhat longer time than 

 in the circulation: for two or three days (up to six days in a single 

 case). In all instances they have disappeared long before the 

 immunity is established. Let us repeat that tjiis 'applies only 

 to the case where the introduction of the bacteriophage into the 

 organism takes place in a territory free from the infection. We 

 have seen, for example, that five months after the termination 

 of an epizootic of barbone it is still possible to isolate a bacterio- 

 phage active for the pathogenic bacterium from the excreta of 

 buffaloes which have resisted. On the other hand experimenta- 

 tion in the chicken has shown us that the activity of the bacterio- 

 phage for the pathogenic bacillus is maintained just as long as 

 the experimental animal continues to ingest these bacteria. 



2. Bablet has shown that the bacteriophagous germs are de- 

 stroyed by preservation for a week in glycerine. We know that 

 this substance exerts no destructive influence on either the dias- 

 tases or the toxins. It may be assumed, therefore, that in a 

 mixture of bacteriophage culture and glyceririe the ultramicrobes 

 alone will be destroyed while the immunizing substances con- 

 tained in the medium will remain intact. Starting from this 

 hypothesis, we mixed 0.5 cc. of a culture of the anti-barbone 

 bacteriophage with 9.5 cc. of glycerine. After holding the mixture 

 at incubator temperature (37°C) for ten days, and after we were 

 assured that the bacteriophagous ultramicrobes were effectively 

 destroyed, we inoculated two steers with this liquid, diluted in 

 500 cc. of saline. Each steer received then 0.25 cc. of the original 

 culture. Tests after forty-five days, respectively with 5 and 50 

 fatal doses of a culture of the bacterium of barbone, showed that 

 these two animals resisted. They had acquired an immunity in 

 spite of the destruction of the bacteriophagous ultramicrobes. 



In the case of experimental barbone the tests were made in a 

 barbone-free region, and the principle which is responsible for 

 the development of the immunity is most probably constituted 

 of the substance of the bacterial cells. The role which the bac- 

 teriophage plays here is to dissolve the bacteria, in which condi- 



