Fishes Pholuhlepharon and Anomalops. 59 



rhaiioff has inoculated tliein in frogs and produced luminous animals. 

 However, non-luminous strains of luminous bacteria have been de- 

 scribed by Beijerinck. There is a possibility, then, that the growth 

 I observed on my culture media was the form which produced light 

 under special conditions of the luminous organ of the fish. On the 

 other hand, although the transfer was made with sterile instruments 

 from the interior of the organ, there is ahvays the possibility of 

 contamination, and nothing certain can be stated regarding the nature 

 of the cultures obtained. 



The culture media used were the following: 



1. Sterile muscle of Anomalops in sea-water. 



2. Unsterile muscle of Anomalops in sea-water. 



3. Sterile muscle of Photoblepharon in sea-water. 



4. Unsterile muscle of Photoblepharon in sea-water. 



5. Potato slab (sterilized) in sea-water. 



6-12. Agar-peptone-amino-acid-sea-water of a reaction varying from colorless 

 to decidedly pink to phenolphthalein. 



The culture medium for 6 to 12 was made by digesting the white 

 of one boiled egg for 24 hours with trypsin solution in 50 c. c. water, 

 diluting to 425 c. c. with sea-water, adding 1.5 per cent agar-agar, and 

 sterilizing. The material was then tubed and NaOH added in suc- 

 cessively increasing amounts to each tube to give a range of acidity 

 on each side of neutrality. These tubes all produced a good growth 

 of bacteria, except the deep-pink decidedly alkaline ones; 5 produced 

 no (?) growth; 1 to 4 abundant grow^th of bacteria. The best growth 

 occurred on the light-pink medium. No light appeared in any tube. 

 Further work is therefore necessary to settle this interesting and 

 important question of the artificial cultivation of bacteria from the 

 luminous organs of Anomalops and Photoblepharon. 



SUMMARY. 



The light of the luminous fishes Photoblepharon and Anomalops 

 appears to be due to luminous bacteria living in the luminous organ. 

 Previously the organ had been considered a gland, producing a 

 luminous secretion oxidized within the gland. Despite the general 

 appearance of an organ of secretion, no luminous material is excreted 

 to the sea-water by the living fish. If the organ is teased in sea-water 

 and examined under the microscope, innumerable motile rod-shaped 

 bacteria, sometimes forming spirilla-like chains, can be seen. Stained 

 smears of the organ show the bacteria nicely. 



In chemical respects an emulsion of the organ behaves just as an 

 emulsion of luminous bacteria and differs in one way or another 

 from extracts of other luminous animals. These various charac- 

 teristics are as follows: 



1. The light-organ is extraordinarily well supplied with blood-vessels and the 

 emulsion is fully as sensitive to lack of oxygen as are luminous bacteria. Light 

 ceases very quickly in absence of oxygen. 



