200 BIOLOGY OF SPECIALIZED GROUPS 



any phosphorescence. His experiments showed that horse 

 flesh (65 per cent of samples) and cattle flesh (89 per cent 

 of samples) when placed in three per cent sodium chloride and 

 allowed to stand in the air became phosphorescent and the 

 bacteria could be isolated. 



Oxygen Requirements. Oxygen is absolutely necessary 

 for the production of light by bacteria. Phosphorescence is 

 an oxidation phenomenon. Under anaerobic conditions the 

 photogenic bacteria grow slowly but do not produce any 

 light until aerobic conditions are provided. When a highly 

 combustible carbohydrate food is present, phosphorescence is 

 greatly increased. 



Fischer calls attention to the well-known fact that phos- 

 phorescence is not nearly so marked in smooth sea water as it 

 is in rough, and is most noticeable on the crest of the waves 

 and in the wake of a ship where the water is churned up. 

 When the oxygen of the air comes in contact with the phos- 

 phorescent material, as it does w r hen the sea water is disturbed, 

 the light produced is greatly augmented. 



Temperature Requirements. The temperature at which 

 light production takes place is subject to great variation. 

 The limits of phosphorescence, according to E. F. Smith, are 

 from -5 C. to 28 C. Light production seems to be the most 

 intense from 5 C. to 20 C. The phosphorescent bacteria 

 of the Baltic Sea and the North Sea flourish best at 18 C., 

 but can grow well at o C., resembling in this respect other 

 inhabitants of the Northern waters. 



