130 THE BACTERIOPHAGE AND ITS BEHAVIOR 



5. BACTERIOPHAGY UNDER THE MICROSCOPE 



We have already seen how the destruction of the bacteria takes 

 place through the action of the bacteriophage. Here are a few other 

 observations made in studying the course of bacteriophagy with B. 

 dysenteriaeP'^ 



We know that if the inoculation of the bacteriophage has been 

 massive, all of the bacteria are attacked at the outset; the fixation of 

 the corpuscles takes place immediately. If a very active race of the 

 bacteriophage is used, within 2 or 3 hours the medium commences to 

 clear little by little, and becomes completely limpid after a short time. 

 If, on the contrary, the inoculation is minimal, the few corpuscles 

 inoculated only affect an equal number of bacteria; the great majority 

 remain unaffected and multiply as they would in a normal medium. 

 But the corpuscles likewise multiply, following a progression more 

 rapid than that pursued by the bacteria, so that within a few hours 

 their number becomes equal to, or greater than, that of the bacteria. 

 This is the time when macroscopic dissolution becomes evident. 



Let us consider the first case, that of the massive inoculation. If we 

 take from time to time a drop of the suspension up to the point when 

 dissolution 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 

 inoculated with 0.1 cc. of a suspension of the bacteriophage and incu- 

 bated at 37°C. 



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 bacilh 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 al- 

 ready dissolved 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 



