BACILLUS BOTULINUS AND ITS SPORES 557 



growth at 11 days yet apparently not surviving 10 per cent salt 

 at the end of 49 or even 31 days. All the other strains with two 

 exceptions gave good growth every day for seven or eleven days 

 after inoculation, and in addition, from 27 to 49 days after 

 inoculation, in 10 per cent salt broth. Quantitative results were 

 not obtained except in that a loop transfer from the 10 per cent 

 salt broth culture gave a definite and decided clouding in the 

 alkaline glucose pork gelatin-broth in 24 hours in every case 

 as stated, with but two or possibly three exceptions. These 

 results were checked microscopically. 



These data prove quite conclusively that a large number of 

 strains of B. botulinus are not inhibited by percentages of salt 

 ranging from 1 to 10, when growing in a medium of an alkalinity 

 of —0.5. This may not signify that B. botulinus will survive 

 10 per cent or less salt used in pickling, as the additional factor 

 of acidity enters here, and this anaerobe is said to be injured — 

 some strains quite decidedly so — by even a slightly acid medium 

 (+0.5 to +0.8). However, the results obtained above seem to 

 indicate strongly that it is not the salt which is the inhibiting 

 factor in the destruction of B. botulinus and its spores by pickling 

 solutions. 



The data for the above tables were worked out by Miss Ruth 

 Normington, a post-graduate student. 



