IMMUNIZATION WITH BACTERIOPHAGE SUSPENSIONS 533 



continued the experiments on the duration of the immunity to barbone, 

 showing that even 14 months after an immunizing injection of the 

 Barbone-bacteriophage a very considerable immunity remained. 



As a result of these experiments, Le Louet, who in the meantime had 

 become Inspector-General of the Veterinary Service of Indo-China, 

 applied this process of immunization on a large scale. The bacterio- 

 phage suspensions virulent for Pasteurella hovis were prepared at the 

 Pasteur Institute at Saigon. By September, 1923, 12,000 buffaloes 

 had been immunized, and the first results on this group were reported 

 by Le Louet at the Congress of the Tropical Medical Association of the 

 Extreme Orient (Singapore, September, 1923). 



He stated that up to that time, none of the 12,000 buffaloes which 

 had been immunized had contracted the disease, despite the fact that it 

 was prevalent in Indo-China. 



Since then, the vaccinations have been continued. The mortality 

 from barbone among the buffaloes has been reduced to actually nothing, 

 and according to Le Louet'"'^ it appears as though the foci of the disease 

 have died out. 



Comment on these results is unnecessary. 



4. IMMUNIZATION AGAINST BACILLARY DYSENTERY 



"The cultures of Shiga lysed by the invisible microbe, which are in 

 reality cultures of the anti-microbe, possess the property of immunizing 

 the rabbit against a dose of Shiga bacilli which will kill the controls in 

 five days." This statement is taken from my first communication on 

 the bacteriophage. The experimental data upon which this affirmation 

 was based are given in the following protocols. 



The rabbit, although naturally refractory to bacillary dysentery is, 

 on the contrary, susceptible to the inoculation of dysentery toxin. This 

 animal could, then, be utilized for the -preliminary antitoxic immuniza- 

 tion experiments. The following experiments showed at once that the 

 Shiga-bacteriophage suspension, a short time after dissolution, is toxic, 

 although to a less degree than is a normal culture of Shiga bacilli. 



Rabbit No. 1. One cubic centimeter of a normal culture of Shiga 

 bacilli was injected intravenously on August 10. The animal died on 

 August 16. 



Rabbit No. 2. Two cubic centimeters of a normal culture of Shiga 

 bacilli were injected subcutaneously on August 10. The animal died 

 on August 16. 



Rabbit No. 3. One cubic centimeter of a Shiga bacillus culture which 



