62 THE BACTERIOPHAGE 



up to the point when lysis is complete, spread these drops on 

 slides and stain, either with the Gram stain, with carbol-thionin, 

 or by the Romanowsky-Giemsa method (all staining methods 

 give essentially the same picture), results such as the following 

 are secured. 



A suspension of Shiga bacilli, 250,000,000 per cubic centimeter, is inocu- 

 lated with 0.1 cc. of a culture of the bacteriophage and incubated at 37C. 



After fifteen minutes it appears as a culture of normal bacilli. 



After thirty minutes it appears essentially the same, except that a few 

 of the bacilli are poorly stained. 



After forty-five minutes about 10 per cent of the organisms stain poorly. 



Between one and two hours, the number of bacilli which stain badly 

 continues to increase, and after 2 hours only a rare cell can be found which 

 has taken the stain normally. At the same time, amorphous debris and 

 granulations, derived most certainly from the bacteria already lysed, are 

 seen. Similar material is seen very abundantly in old normal cultures of 

 the Shiga bacillus. These granulations dissolve more slowly than the 

 remaining portions of the bacterial protoplasm. Finally, and this is a most 

 important point, spherical forms, more or less ellipsoidal, of variable dimen- 

 sion, always rare, measuring 4 to 7 by 3 to 5 n may be detected. We will 

 see in a moment to what they are due. There are occasional bacillary 

 forms, well-stained, having a length of from 8 to 12 p. 



Between the second and third hours the amorphous debris considerably 

 augments and the bacillary forms rapidly disappear. A few spherical 

 forms are still to be seen. 



After four hours lysis becomes more and more complete. Only a single 

 poorly stained bacillus will be found in two or three fields. 



Gradually the formless debris disappears, and, in turn, the granules. 

 After thirty-six hours nothing whatever can be distinguished in stained 

 preparations. 



With the ultramicroscope at no time can there be seen elements 

 other than the bacilli (whose number gradually diminish, to 

 disappear entirely in about two hours) and the extremely fine 

 granules. It can hardly be said that the latter represent formed 

 elements. At the beginning the bacilli present a normal appear- 

 ance. After forty-five to sixty minutes fine granules are seen, 

 ever becoming more and more abundant, within the interior of 

 the bacterial cells. The number of bacterial cells containing 

 granules also rapidly increases with a corresponding diminution 

 in the number of normal bacilli. The most interesting part of 

 the observation 8 is that within one and one-quarter to one and 



8 First noted by P. Jeantet. 



