402 THE BACTERIOPHAGE AND ITS BEHAVIOR 



neutralizing action of bacterial extracts for the serum. Table 52 indi- 

 cates the results obtained in one experiment of this type. 



Hauduroy^^^ has also worked on the question of the inhibiting action 

 of antibacterial sera and reached the conclusion that an inhibition does 

 occur. But according to his protocols it requires far greater quanti- 

 ties of serum than is indicated by the experiments of da Costa Cruz. 

 Hauduroy distributed a young culture of B. dysenteriae Shiga in tubes, 

 10 cc. to each, and inoculated each one with 1 drop of a suspension of 

 the bacteriophage. He then added the anti-Shiga serum in quantities 

 varying from 2 to 10 drops. Bacteriophagy took place normally. 

 When the serum was added in quantities of between 12 and 34 drops 

 the bacteriophagic process was retarded. It was only when the quan- 

 tity of serum added was above 36 drops that inhibition occurred. 



Studying the phenomenon further, he found that the inhibitory 

 action was not due to some effect upon the bacteriophage itself, for if 

 he filtered a suspension which remained turbid because of the large 

 amount of added serum, he found that the bacteriophage was still 

 alive and virulent in the filtrate. He concluded that the process 

 of bacteriophagy was held in abeyance because some substance, se- 

 creted by the bacterium and essential to bacteriophagy, was flocculated 

 by the serum. 



If we consider the question as to the mechanism whereby an anti- 

 bacterial serum may be inhibitory we immediately discover that 

 there are two possible hypotheses which would explain the facts ob- 

 served, and not a single explanation, as Hauduroy seems to believe. 



The antibacterial serum exerts no direct action upon the bacterio- 

 phage protobe, as experiment shows. Consequently, the inhibiting 

 action must be dependent upon some modification of the bacterium or 

 upon some product elaborated by the bacterium. 



We have seen in the section dealing with the nature of the bacterio- 

 phagic process that although the bacterium acted upon is in a medium 

 containing quantities of an antiseptic which do not prevent its multi- 

 phcation, the bacteriophage may, nevertheless, remain inert. The 

 inhibiting action of the antibacterial serum can be explained perfectly 

 upon the same basis, it making no difference whether the action is 

 exerted by an antiseptic or by an antiserum. 



On the other hand, we know that the first step in the phenomenon 

 of bacteriophagy consists in the approach of the corpuscle to the sus- 

 ceptible bacterium. As the antibacterial serum most certainly modi- 

 fies the surface tension of the bacterium, we have no reason to beheve 



