AXTISEPTIC8 147 



CONTROL -NO DRUG 



Fig. 30. Multiplication curves of Salmonella enteritidis with and 

 without sulfathiazole. Abscissa: time in hours; ordinate: logarithm 

 of the number of organisms per cc. (From Muir, Shamleffer and 

 Jones, 1942.) 



tions the generation time in broth increases from 17 to 90 

 minutes with 50 piDm. thiazole and to 120 minutes with 

 100 ppm. In a synthetic medium, 6 ppm. is sufficient to 

 stop growth completely after multiplication has taken 

 place quite normally for 10 hours. The type of curve 

 suggests a deficiency of a necessary cell construction 

 material in the medium. 



This delay is not caused by a very slow penetration of 

 the drug into the cells, as is proved by the fact that 

 the luminescence of three species of photogenic bacteria 

 was inhibited without delay as soon as the cells came 

 in contact with sulfanilamide (Johnson and Moore, 1941). 



The assumption of a slow penetration is also contra- 

 dicted by the following studies of Kohn and Harris 

 (1941a) with resting cells: They inoculated Bacterium 

 coli into two tubes of culture medium held at 5°, one of 

 which contained a retarding dose of sulfonamide. (At 5°, 

 Bacterium coli does not grow.) After 3 hours, an equal 

 amount of sulfonamide was added to the other tube, and 

 both were incubated at 30°. The delay of the growth re- 



