PREVITE AND BERRY 



Days Post Number of survivors at 

 Infection 5° C 15«> C 25° C 





 2 



6 



8 



10 



12 



lU 



Table I.Survivalof mice infected with 10 ^ Salmonella 

 typhimurium . SH-U-A. (Derived from data presented 

 in J. Infect. Dis. 110: 201-209. 1962.) 



according to the method of Reed and Muench (1938), 



RESULTS 



Infection with S. Typhimurium, SR-U-A 



Mice were infected intraperitoneally with 10^ viable cells of 

 S. typhimurium , SR-U-A. This strain was derived by chance from 

 an agar slant culture of SR-U which had been stored at 5° C for a 

 period of several months. On transfer to brain- heart infusion broth 

 and injection into mice, it was found to have lost much of its viru- 

 lence. The animals were divided into three groups and placed at 

 temperatures of 5° C, 15° C, and 25° C immediately after infection. 

 The pooled results are presented in Table I, None of 42 mice sur- 

 vived at 5° C while 25 per cent (8 of 32) of those at 15° C and 39 per 



218 



