132 THE BACTERIOPHAGE AND ITS BEHAVIOR 



previously been counted. By such a procedure it is found that in 

 taking two cultures presenting a great difference in count, a parallelism 

 is always to be noted between the counts and the number of granules 

 observed. 



It would likewise be well to recall what we have already seen with 

 reference to the multiplication of the corpuscles, namely, that this 

 multiplication appears to take place in successive jumps (which cor- 

 respond to the rupture of a large number of parasitized bacilli) 

 in which the number of corpuscles liberated after 1| to 1| hours cor- 

 responds to about 18 to each single one inoculated. And we will see 

 that the number of granules consequent upon the rupture of a cell 

 amounts to between 15 and 25. There is, therefore, a great probability 

 that the granules are actually the ultramicroscopic bacteriophagous 

 corpuscles. 



We may consider a second case, that of a minimal inoculation. 

 In this case the medium becomes more and more turbid before disso- 

 lution actually commences. 



A suspension of Shiga bacilli, containing 250,000,000 per cubic 

 centimeter is inoculated with 0.0001 cc. of a suspension of the bacterio- 

 phage, a very active race being selected. 



After 30 minutes the medium has its original turbidity; essentially 

 that of a normal culture of the Shiga bacillus. 



After one hour the original turbidity is still maintained. When 

 smeared and stained all the baciUi are of normal shape, but an occa- 

 sional form stains poorly. 



After two hours the culture is about twice as turbid as at first. 

 There is amorphous debris in the bottom of the tube. All of the bacilli 

 appear to stain normally. Many of the bacilli (about two in every 

 three) are about four times the normal length, that is, of the bacilli 

 used to seed the culture, and there are all intermediary forms. Oval 

 and spherical forms are relatively numerous, but they are always 

 fewer than would be expected from a comparative ultramicroscopic 

 examination. These forms are indeed very fragile and are particularly 

 liable to destruction during fixation upon the slide so that their demon- 

 stration in stained preparations requires great care. 



After three hours the suspension is slightly cloudy. The bottom of 

 the tube is covered with fine debris without definite form, with, from 

 place to place, great amorphous masses and numerous granules re- 

 sembling those encountered in very old cultures of normally grown 

 Shiga bacilH. Only a single spherical fonn can be detected in a ten- 



