BACTERIOLYSIS 29 



drops, and to the third, two cubic centimeters. With each set 

 the procedure is that already indicated for the Shiga organism. 

 In routine work a single tube can be used in place of the three 

 tubes, and to this ten drops of the nitrate is added, but with this 

 simplified technic the danger lies in the fact that a bacteriophage 

 of weak activity may not be detected. 3 



TECHNIC FOR ENHANCING VIRULENCE 



It has already been stated that a bacteriophage may be present 

 even though it is unable to induce the slightest macroscopic evi- 

 dence of the lysis of a bacterial suspension. Indeed, this is the 

 situation most frequently encountered in the process of isolation 

 However, it is, as a rule, easy to increase the activity of such a 

 bacteriophage. One of the following methods suffices: 



3 Mention may be made here of a method of Bordet and Ciuca, and it is 

 upon this procedure, moreover, that these authors have based their theory 

 of hereditary lysis. They inoculate a guinea pig intraperitoneally at three 

 or four different times at intervals of a few days with a culture of B. coli. 

 The day after the last injection, according to them, it is only necessary to 

 wash out the peritoneal cavity, whereupon the principle giving rise to 

 "hereditary lysis" is found in the exudate. From their first communication 

 on the subject it is evident that they consider this observation a specific 

 example of a general law — which indeed would be one of the sine qua non 

 conditions for the validity of their theory — that an injection of any bac- 

 terium causes the organism to respond with the production of a principle 

 which gives birth to the phenomenon of lysis in series. They stated that 

 they would shortly announce the results secured with diverse bacteria 

 but this communication has never appeared . I have tried without success, 

 as have several other investigators, to duplicate the results described by 

 Bordet and Ciuca. In reality, in this experiment, there has been a passage 

 of the anticoli bacteriophage, which, as experiment shows, is normally 

 present in the guinea pig intestine, into the peritoneal cavity as a result of 

 the irritation induced by the inoculations. After its appearance in the 

 peritoneum it multiplies there by virtue of the B. coli inoculated. The 

 correctness of this interpretation is vouched for by the fact that the results 

 reported by Bordet and Ciuca can be secured if, a few hours before the 

 intraperitoneal injection of bacterial culture, the bacteriophage active 

 for this bacterial type is given the animal per os . The active bacteriophage 

 found in the intestine passes through into the peritoneal cavity. The 

 method of Bordet and Ciuca gives results only by accident, only when 

 an active bacteriophage was previously present in the intestine. Thus, 

 all of the conclusions of these authors fall ipso facto. We will return else- 

 where to this question (Chapter VI, Nature of the Bacteriophage). 



