IMMUNIZATION WITH BACTERIOPHAGE SUSPENSIONS 517 



and the remaining 40 received an injection of bacteriophage suspen- 

 sion. The disease suddenly stopped in the lot which had received 

 the bacteriophage, while the mortality continued without diminution 

 in the group which had received the serum. After a few days, the 

 survivors of the serum-treated lot were inoculated with 1 cc. of bac- 

 teriophage suspension. Thereupon the mortality in this group sud- 

 denly stopped. 



Observation 8. Epizootic due to B. gallinarum. 



There had been 3 to 4 deaths per day. An injection of 1 cc. of 

 bacteriophage suspension was given to each of the 100 survivors. 

 The epizootic was immediately and permanently arrested. 



Observation 9. An enzootic involving a group of farms. 



On one of the farms 98 out of a total of 150 pullets had died within 

 the past 6 months. The mortality was very irregular; some weeks 

 none of the animals died, in others as many as 12 succumbed. Among 

 the survivors, 25 were inoculated with 0.5 cc. of the bacteriophage sus- 

 pension, the other 27 with 1 cc. The disease disappeared from this 

 l^arn-yard from the day of the inoculation, although it continued as 

 before to destroy the animals of the neighboring farms where the pul- 

 lets had not been immunized. 



Observation 10. Epizootic due to B. gallinarum. 



Out of a total of 140 chickens, 15 had died within 4 days. Each of 

 the survivors received an injection of 0.5 cc. of a bacteriophage sus- 

 pension. Three chickens which were very sick at the time of inocula- 

 tion died; no further deaths occurred. 



Observation 11. Epizootic due to B. gallinarum. 



The record showed 150 deaths within the past 2 months, out of a 

 total number of 400. The 250 survivors received an injection of 0.5 cc. 

 of a bacteriophage suspension. In the 2 months which followed a few 

 of the pullets died from time to time. A second injection of 0.1 cc. of 

 bacteriophage suspension was given. Thereupon the enzootic stopped 

 permanently. 



Here, as a result of the first injection, the epizootic assumed the 

 character of an enzootic, and a second injection was necessary to 

 arrest the enzootic. 



Observation 12. Epizootic due to B. gallinarum. 



This outbreak took place on a farm which had three separate chicken 

 yards. The epizootic began in yard No. 1, containing 225 chickens. 

 The mortality here was 7 to 8 per day. The disease next extended to 

 yard No. 2; and at the time when the experiment began it had not 

 yet reached yard No. 3. 



