IMMUNIZATION WITH BACTERIOPHAGE SUSPENSIONS 519 



received an injection of 0.1 cc. of the bacteriophage. A large number 

 of these animals were already showing symptoms at the time of the 

 inoculation. All of the sick chickens recovered and the epizootic 

 permanently disappeared. This experiment confirms that recorded 

 above, in that it shows that the effective principle is the bacteriophage 

 protobe itself, functioning because of its virulence. The dissolved 

 bacterial substances do not contribute in any way to the processes of 

 immunity which iynmediately follow the inoculation. 



Observation 16. Epizootic due to B. gallinarum. 



Within the past month there had been 23 deaths. The 71 survivors 

 received an injection of 0.1 cc. of a bacteriophage suspension. The 

 epizootic stopped immediately and completely. 



Observation 17. Epizootic due to B. pullorum A. 



This started in a brood of chicks when they were 4 days old. Be- 

 tween the 5th and 10th days there were 80 deaths out of a total of 137. 

 On the 10th day the chicks ingested with the drinking water a suspen- 

 sion of bacteriophage which was virulent for both B. gallinarum and B. 

 pullorum. Three more chicks died and then the disease was arrested. 



Observation 18. Epizootic due to B. -pullorum A. 



This epizootic was also among young chicks. The Gallinarum- 

 bacteriophage showed a definite virulence for the B. pullorimi isolated 

 from the intestine of one of the chicks of this brood which had died. 

 Of the 500 chicks, 150 had died within the first two weeks after hatch- 

 ing. The survivors ingested a suspension of bacteriophage mixed in 

 the drinking water. The epizootic was transformed into an enzootic, 

 that is, the disease persisted but with a lessened and very irregular 

 mortaHty. 



Observation 19. Epizootic due to B. pullorum. 



This developed among chicks 6 days old. Here again the bacterio- 

 phage was administered by ingestion in the drinking water. The race 

 used was virulent for B. gallinarum. Out of a total of 500 chicks, an 

 average of 16 had died daily prior to the ingestion. An in vitro test 

 showed that the Gallinarum-bacteriophage possessed also a strong 

 virulence for a strain of B. pullorum isolated from a chick of this hatch- 

 ing which had died. This bacteriophage was mixed with the drinking 

 water. The mortality diminished considerably, although during the 

 few days following the ingestion 30 chicks died. The suspension was 

 again added to the water and a second ingestion was accomplished. 

 From this time on the disease disappeared completely. 



Observation 20. Epizootic in 14 day old chicks. 



