114 THE BACTERIOPHAGE AND ITS BEHAVIOR 



require an hour of continuous search and observation before the first 

 rupture is seen. It is for this reason that those who desire to witness 

 this curious phenomenon should use Shiga bacilh in contact with a 

 highly potent bacteriophage. When they have once observed the 

 reaction, recognizing the manner in which it takes place, they can then 

 investigate other cases where the phenomenon is less conspicuous. 



Personally, I have observed the rupture of bacteria contaminated 

 by bacteriophage corpuscles with B. dysenteriae Shiga and Flexner, 

 with B. typhosus and the paratyphoid strains, with B. pestis, and 

 with the staphylococcus. As a matter of fact, I have never failed 

 to see it when I have sought for it. With the staphylococcus the 

 individual coccus undergoing rupture will have a diameter 2 to 3 times 

 as great as that of a normal coccus. 



The rupture of bacteriophaged bacteria has also been observed by 

 da Costa Cruz,^^^ Pondman,^^^ as well as by Hauduroy^^^ and by Flu. 



Naturally, a quite logical question is. How can the bacteriophage 

 corpuscle penetrate the bacterium? The following observations per- 

 mit an hypothesis, although they do not give a clear and complete 

 picture of the mechanism. 



At the moment when bacteriophagy is most intense we see by dark- 

 field observation that the single unusual feature presented by the 

 bacteria is a more or less outspoken swelling. None of the bacteria 

 appear damaged, and with the exception of the ''floccules" which follow 

 the bursting and which disappear after a few minutes there is no bac- 

 terial debris. If a drop of the suspension in which the process of 

 rupture is taking place is removed and spread upon a slide, dried, and 

 stained, it will be seen that along with the normal bacteria there are 

 some swollen organisms and some amorphous material which certainly 

 represents stained floccular material. In such a stained smear the 

 background is not colorless as in an ordinary preparation of a suspen- 

 sion of normal young bacteria, but is tinted. All of the bacteria are 

 sharply defined, even those which are distended. 



Another interesting situation develops if we take a drop of the 

 suspension when bacteriophagy is at its maximum and place it between 

 a shde and cover-glass (selecting a thick cover-glass to avoid breakage) 

 exerting strong pressure upon the cover, as though a crushing of the 

 bacteria was desired. Allow the preparation to dry in the incubator, 

 then, after removal of the cover-glass, fix the smear and stain with 

 any of the ordinary dyes (Loeffler's blue, carbol-f uchsin) . Examina- 

 tion will reveal many of the bacteria presenting a curious appearance, 

 for about some of the well-stained bacterial cells may be seen one, two, 



