152 BACTERIA, YEASTS, AND MOLDS 



very slowly, and the food may therefore be preserved for 

 quite a long period, although it is sure in the end to 

 undergo certain forms of putrefaction. 



The type of putrefaction that occurs in material kept 

 in an ice chest is usually somewhat different from that 

 which occurs in the same material at an ordinary room 

 temperature. The common putrefactive bacteria grow 

 readily at high temperatures, but hardly at all at the 

 temperature of the ice chest. Other types of bacteria, 

 however, grow more readily at the lower than at the 

 higher temperatures, and meat or other food kept in the 

 refrigerator will in the course of time undergo a type 

 of decay due to the microorganisms favored by the low 

 temperature. This decayed meat appears somewhat dif- 

 ferent from decayed meat at higher temperatures and has 

 a different odor,^ — a fact indicating a different type of pu- 

 trefaction. Certain peculiar kinds of decay are seen at 

 these low temperatures which are hardly found under 

 other conditions. Occasionally, for example, fleshy foods, 

 particularly those from salt water, like lobsters or fish, 

 develop a peculiar phosphorescence if kept in an ice chest. 

 If examined in the dark they will be seen to glow with a 

 somewhat brilliant greenish light. This phosphorescence 

 is due to the development of certain very interesting kinds 

 of bacteria, and always appears if they grow luxuriantly 

 at low temperatures. They grow chiefly upon foods which 

 contain considerable salt, and hence particularly in marine 

 foods. They are more likely to be found in meat pre- 

 served in an ice chest, since the more common decay 

 produced by other bacteria will at higher temperatures 

 mask the growth of the phosphorescent bacteria. It is 



