viii Contents 



PAGE 



Multiple mechanisms of acquired drug resistance 



by Margaret J. Thornley, Jehudith Sinai and John 



YUDKIN ........ 141 



Discussion: Davis, Dean, Fredericq, Fulton, Hotchkiss, 



Hughes, Pollock, Rose, Slonimski, Walker, Yudkin . 161 



Physiological (phenotypic) mechanisms responsible for 

 drug resistance 



by B. D. Davis 165 



Discussion: Davis, Eagle, Knox, Pollock, Pontecorvo . 180 



Genetic and metabolic mechanisms underlying multiple 

 levels of sulphonamide resistance in pneumococci 



by RoLLiN D. Hotchkiss and Audrey H. Evans . 183 



Discussion: Cavalli-Sforza, Davis, Demerec, Hotchkiss, 



Lederberg, Pontecorvo, Stocker .... 193 



The phenotypic expression of genes determining various 

 types of drug resistance following their inheritance by 

 sensitive bacteria 



by W. Hayes . . 197 



Discussion: Barber, Cavalli-Sforza, Davis, Fredericq, 

 Hayes, Hotchkiss, Lederberg, Pollock, Pontecorvo, 

 Stocker ......... 205 



Specific polyhydroxy compounds as cofactors of enzymic 

 adaptation and its inheritance 



by P. P. Slonimski and H. de Robichon-Szulmajster 210 



Discussion: Davis, Fulton, Pollock, Slonimski, Wester- 



GAARD ......... 230 



Development of resistance to streptomycin in Serratia 

 marcescens 



by B. Gyorffy and I. Kallay ..... 233 



Discussion: Cavalli-Sforza, Davis, Dean, Eagle, Fulton, 

 Gyorffy, Hayes, Hotchkiss, Knox, Lederberg, Stocker, 

 Yudkin ......... 237 



Distribution of drug -resistant individuals in cultures of 



Mycobacterium tuberculosis 



by R. Knox 241 



Discussion : Davis, Dean, Eagle, Hayes, Knox, Lederberg, 



Pollock, Pontecorvo, Stocker, Westergaard . . 246 



