DEPARTMENT OF MARINE BIOLOGY. 197 



innumerable motile, rod-shaped bacteria, sometimes forming spirilla-like 

 chains, can be seen. Smears of the organ which I obtained in Banda have 

 been very kindly stained for me by Professor Dahlgren, of Princeton Uni- 

 versity, and show the bacteria nicely. 



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

 of luminous bacteria and differs in one or another way from extracts of other 

 luminous animals. These various characteristics may be summarized as 

 follows : 



1. The light organ is extraordinarily suppUed with blood-vessels, and the 

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

 Light ceases very quickly in the absence of oxygen. 



2. If dried, the organ will give only a faint light when again moistened 

 with water. This is characteristic of luminous bacteria. The luminous 

 organs of most other forms can be dried without much loss of photogenic 

 power. 



3. Luciferin and lucif erase can not be demonstrated. This is also true of 

 luminous bacteria. 



4. The light is extinguished without a preliminary flash by fresh water and 

 other cytolytic (bacteriolytic) agents, characteristic also of luminous bacteria. 



5. Sodium fluoride of 1 to 0.5 per cent concentration extinguishes readily 

 the light of an emulsion of the gland. 



6. Potassium cyanide has an inhibitive effect on light production in about 

 the same concentration as with luminous bacteria. 



To these observations must be added the very suggestive fact that the 

 light of Photohlepharon and Anomalops continues night and day without 

 ceasing and quite independently of stimulation. This is characteristic of 

 Imninous bacteria and fungi alone among organisms, and very strongly sug- 

 gests that the hght is actually due to sjinbiotic luminous bacteria. The 

 organ thus appears to be an incubator for the growth and nourishment of 

 these forms. 



Actual proof that the bacteria found in the organ are luminous can only 

 come when these are grown artificially. My attempts in this direction have 

 failed. Good growths of bacteria were obtained on pepton agar, but they pro- 

 duced no light. One might expect that a symbiotic form would require rather 

 definite food materials to produce light, and it is perhaps not surprising that 

 culture experiments have failed. Certainly, the ocular and chemical evidence, 

 if not the cultural evidence, supports the view that the Hght of these living 

 fish is bacterial in origin. A complete account of the fish will appear shortly 

 in the Carnegie Institution publications. 



An account of luminescence among coelenterates, so abundant in Puget 

 Sound, will appear in the Biological Bulletin. Work on specificity and chem- 

 ical character of luciferin is being continued. 



Report on the Polychcete Annelids of Montego Bay, Jamaica, hy A. L. Treadwell. 



From June 28 to July 21 was spent in Montego Bay, Jamaica, completing 

 data on the species of the West Indian Leodicidse for a pubHcation on this 

 family now in press ; little attention was paid to members of other polychsete 

 famihes. Montego Bay proved to be rather poor in annelids, as there are 

 few mud flats and the dead, porous coral rock which affords such favorable 

 hiding-places for these animals is largely absent from the splendid coral reefs 

 of this bay. The area covered was from White House, about a mile east of 

 the harbor entrance, along the shore of the bay as far as Unity Hall, on the 



