58 



The Production of Light by the 



action of KCN on an emulsion of the luminous organ of Photo- 

 hlepharon. The KCN was dissolved in sea-water, and this solution 

 was diluted with an equal volume of sea-water each time. The con- 

 centration of KCN necessary to inhibit luminescence of these fish 

 is sufficiently close to that inhibiting the luminescence of bacteria 

 to supply one more fact in favor of the view that the light of Pkoto- 

 blepharon and Anomalops is of bacterial origin. 



TabIjE 2. — Effect of KCN on Emulsion of Phoiohlepharon Luminous Organ. 



CULTURE EXPERIMENTS. 



Despite the parallel in behavior of an extract of the luminous 

 organ of these fish and an emulsion of luminous bacteria, final proof 

 of the bacterial nature of the light must come with the artificial 

 cultivation of the organisms. Although not equipped for bacteri- 

 ological work in Banda, I have endeavored to obtain luminous cul- 

 tures by growth of bits of the luminous gland on various media. 

 Growth of some kind of organism has been abundant, but no light 

 has appeared in any case. It is possible that this growth was actually 

 made by the luminous organism, but that no light was produced under 

 artificial conditions. Giard and Billet have described a malady of 

 sand-fleas, an infection of the animals with luminous bacteria, which 

 eventually led to their death. They were able to inoculate unin- 

 fected sand-fleas, which would then become luminous, with the organ- 

 isms, and grow them on artificial media, but light never appeared 

 under these artificial conditions. However, the cultures inoculated 

 into living sand-fleas would luminesce in the animal. Apparently 

 some special nutrient material is necessary for luminescence in this 

 particular organism, and it is not improbable that a luminous bac- 

 terium which has developed into a symbiotic organism, such as we 

 may suppose to be present in these fish, would require special nutrient 

 substances. The ordinary luminous bacteria of the sea can be grown 

 and luminesce with great regularity on almost any medium. Tar- 



