BACTERIOPHAGOUS ULTRAMICROBE 123 



intensity with various nuclear staining reagents. Between the 

 nucleolus and the nuclear membrane is a space filled with the 

 nuclear fluid. 



The zoospore of Nucleophaga amoeba first penetrates the proto- 

 plasm of the amoeba but it never develops there; it passes into 

 the nucleus through the membrane which it perforates, most cer- 

 tainly through the aid of a dissolving diastase. Dangeard has 

 demonstrated the portal of entrance of the parasite as a minute 

 circular opening, as though made by a punch, persisting after 

 the entrance of the parasite. After its penetration into the nu- 

 cleolus the parasite resembles a refractile corpuscle, increasing 

 slowly in size in proportion as the nuclear substance disappears. 

 When this nuclear material has been utilized completely the entire 

 interior of the nucleus is filled and the membrane is distended. 

 At this time the nucleus of the parasite, up to the present time 

 single, actively divides and when sporulation is effected there 

 are about one hundred regularly spaced nuclei. About each of 

 these nuclei a zoospore organizes, and a sporangium is thus formed, 

 containing distinct, rounded corpuscles, which contain nuclei 

 at the time of sporulation. 



Frequently a single amoeba is parasitized by two or perhaps 

 several zoospores, and in such cases each develops separately and 

 gives birth to a distinct sporangium. When the sporangium 

 reaches maturity the protoplasm of the amoeba disintegrates, 

 the sporangium ruptures, freeing the young zoospores, and these 

 become distributed throughout the medium, ready to parasitize 

 the healthy amoebae in their neighborhood. 



It is evident that I have not made any comparison between 

 Nucleophaga amoeba and Bacteriophagum intestinale, and that 

 these observations are mentioned simply because there is a cer- 

 tain resemblance between the two phenomena of destruction, 

 that of the amoeba and that of the bacterium. 



THE LYSINS OF THE BACTERIOPHAGE 7 



It is obvious that the bacteriophage is unable, merely by its 

 presence, to dissolve a bacterium. This action can only be 

 accomplished through the agency of lytic diastases. 



7 The experiments dealing with the lysins have been performed in col- 

 laboration with G. Eliava. 



