OBSERVATIONS ON THE NATURE OF BACTERIOLY- 

 SANTS (D'HERELLE'S PHENOMENON, BACTERIO- 

 PHAGE, BACTERIOLYTIC AGENT, ETC.) 



PART II ' 



WILBURT C. DAVISON 

 Baltimore, Maryland 



From a consideration of the properties of bacteriolytic filtrates 

 of stool cultures, which I have discussed in part I as well as in a 

 review of the whole subject (Davison, 1922) it would seem pos- 

 sible that the bacteriolytic principle might be an enzyme, although 

 as d'Herelle (Davison, 1922) has pointed out, none of the evidence 

 absolutely disproves his contention that a bacteriophage is a 

 Uving ultra-microscopic filter-passing organism. If then, one 

 assumes that the substance is enzymatic, and that it can only be 

 propagated from generation to generation by passage through 

 living cultures one must conclude that it is contained in the bac- 

 terial cells or is a product of their metabolism. I therefore 

 studied the properties of the colonies of "sensitive" and "normal" 

 strains of Bact. dysenteriae (Flexner). 



STUDY OF THE COLONIES OF A "sENSITH'E" STRAIN OF BACT. 

 DYSENTERIAE (fLEXNER) 



One-tenth cubic centimeter of a bacteriolysant was dropped on 

 the surface of a five-hour agar culture of normal Flexner Y baciUi 

 (Hiss and Russell) and the plate was replaced in the incubator at 

 37°C., for twenty-four hours. At the end of this time, the area 

 bathed by the bacteriolysant was apparently devoid of growth 

 or else covered with a fine film, while the remainder of the plate 



' Presented at the twenty-third annual meeting, Society of American Bacteriolo- 

 gists, December 29, 1921. From the Department of Pediatrics of the Johns Hop- 

 kins University and the Harriet Lane Home of the Johns Hopkins Hospital, 

 Baltimore, Marj'land. 



491 



