262 THE BACTERIOPHAGE 



A single injection of 0.04 cc., or less than a normal sized drop, 

 into a steer of 100 kgms. weight places the animal within 4 

 days in a condition where it can withstand a test inoculation 

 of five fatal doses. Sixty days later the animal resists a 

 test inoculation representing fifty surely fatal doses. 



The blood of an immunized animal injected into a normal 

 animal confers on the latter a passive immunity as solid as 

 that enjoyed by the actively immunized one itself, even if this 

 last one has received but a single injection of 0.04 cc. of culture 

 of the bacteriophage. And this passive immunity, under ex- 

 perimental conditions at least, is still intact forty-five days after 

 the injection of the blood. 



IMMUNIZATION AGAINST DYSENTERY 



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

 are in reality cultures of the anti-microbe, possess the property 

 ctf 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 experi- 

 mental 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 immunization experiments. The following experiments 

 showed at first that the culture of anti-Shiga bacteriophage, a 

 short time after lysis, 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 had 

 been subjected to lysis for six hours was injected intravenously. (The 

 amount of bacillary substance here was the same as in the preceding.) 

 The rabbit lived. 



Rabbit no. 4. Two cubic centimeters of a Shiga culture which had been 

 lysed for six hours were injected subcutaneously. The animal died on 

 August 16. This rabbit had also been injected on August 10. 



