22 Perspecfives in Microbiology 



TABLE II. Control of Toxinogeny in Corynebac+erlum diphtheriae * 



Immunity Immunity 



to 3 to Y Toxinogeny 



* From the results of Groman (4). 



t The status of this strain is not yet dear. Types 1 and 2 have been 

 isolated after exposure of C. diphtheriae (y) to phage (3. 



which may be associated with a structure conferring im- 

 munity against phage y- 



Here, the presence of a prophage of a given genetic con- 

 stitution modifies the bacterium in such a way that it pro- 

 duces toxin when deprived of iron. 



In other cases, the presence of a prophage modifies tlie 

 metabolism of the microbe so that the morphology of the 

 colony is altered. In B. megaterium, the colony type is 

 changed by lysogenization with phages IPT and 3, not 

 with phages IGC and 2. The morphology reverts to the 

 normal when the prophage is lost (5). In this case, as in 

 the case of Corynebacterium diphtheriae, the hypothesis of 

 a selection by the phage of a preexisting bacterial mutant 

 has been ruled out. The new bacterial feature is due to 

 the presence of prophage and disappears when the pro- 

 phage disappears. 



D/SCUSS/O/7 



A cell is an organized totality. The importance of the 

 interrelations and interactions of cell particles and organ- 

 elles has long been recognized, and the life and reproduc- 

 tion of a cell are often visualized as the result of integra- 

 tions at various levels of organization. 



