RECOMBINATION IN BACTERIOPHAGE 



45 



generation, but now including some individuals differing from wild type by 

 both unit changes, and other individuals differing from wild type not at all. 



hr mr 



Figure 1. — Mutational pattern of the bacterial virus T2H. 



The analogy to other genetic recombinations is obvious, and it is natural to 

 look for a common mechanism. 



The procedure of making a cross consists essentially in infecting a measured 

 number of growing bacteria with larger measured numbers of two kinds of 

 virus, diluting the culture before lysis begins to prevent readsorption of viral 

 progeny to bacteria not yet lysed, and plating samples of the total yield of 





\ 



tor 



i 

 i 





Figure 2.— Progeny of the cross mXrl. 



239 



