THE MECHANISM OF BACTERIOPHAGY 131 



less ellipsoidal, of variable dimensions, always rare, measuring 4 to 7 

 by 3 to 5 M 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 yu. 



Between the second and third hours the amorphous debris consider- 

 ably augments and the bacillary forms rapidly disappear. A few spher- 

 ical forms are still to be seen. 



After four hours, solution 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 bacilh (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 appearance. 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 cor- 

 responding diminution in the number of normal bacilli. 



Not all of the amorphous material seen in the stained preparation 

 is to be seen under the ultramicroscope. Apparently, strongly im- 

 bibing water, it assumes the same refractile index as the medium. 

 This amorphous debris is certainly composed of the "floccules" which 

 remain after the rupture of the bacteria, floccules which hydrate gradu- 

 ally and which thus become invisible under the microscope even though 

 they still take the stain. Neither in the stained preparation nor under 

 direct examination can corroded bacteria be observed. 



At the stage of the process when the number of refractile granules is 

 the greatest the swelling of the bacteria, of which we have spoken, 

 is particularly noticeable, and it is interesting to note that these dis- 

 tended bacteria are the ones which contain the greatest number of 

 refractile corpuscles. The number of corpuscles reaches its maximum 

 within those bacteria which are spherical and ready to burst. 



What do the fine granules that can be seen under the ultramicroscope 

 represent? While nothing can be affirmed with absolute assurance 

 there is nothing to preclude the supposition that they represent the 

 corpuscles of the bacteriophage, basing this upon the comparative 

 examination of suspensions in which the number of corpuscles has 



