for 15 minutes to secure the expulsion of air, thus forming a sterile 

 vacuum. This is the general rule followed in most canneries. 



Organisms recovered. Bacteria isolated from the cans were of 

 three types, aerobes, anaerobes, and thermophiles, their frequency 

 being in the order named. The thermophiles found seemed to be all 

 of the same type and no further identification was made of them. 

 Anaerobes were detected but not identified. Having such a large 

 group of aerobes, it was necessary to separate them into types before 

 they could be finally identified, and this was done by subculturing 

 upon potato. By this method many like, or apparently like, organisms 

 separated. Those encountered the greatest number of times were 

 distinguished by the following characteristics: B. subtilis (Ehren- 

 berg), an abundant, beady growth upon potato, turning pink after 

 about the first 24 hours, when incubated at 37° C. ; B. vulgatus 

 (Flugge), large, hanging folds, grayish white in color when incu- 

 bated at ?)7° for 24 hours; and B. mesentericus (Flugge), a light 

 buff, finely wrinkled growth when incubated at 37° from 24 hours to 

 three days. Many organisms found had not been inoculated in the 

 cans, and therefore must have been in the raw fish or cans used in 

 the experiment. The following foreign organisms were recovered 

 from the cans after processing, some of which were isolated from a 

 single colony found on a petri plate : 



Foreign Organisms Recovered 



Of the ten organisms inoculated into the salmon four were recov- 

 ered from eight different cans after processing. These bacteria are 

 given in the following table, with the length of time the can was 

 processed : 



114 



