SUMMARY AND CONCLUSIONS 337 



I have elsewhere ^ described what I believe to be several 

 distinct uses of illumination in living Myctophuin coccoi, 

 and during six years of trawling off Nonsuch we have 

 made many records of flashes or more continuous lighting, 

 in abyssal fish which have survived from ten minutes to as 

 many hours. 



Under cloudy conditions I have detected sparks of light 

 in the bathysphere dives as far up as 400 feet. From 2000 

 feet down, animal light is the only source of external illu- 

 mination. The nonhalation of these lights was marked 

 throughout. This must be due to the clarity of the mediums 

 traversed by the light. At times there were flashes from un- 

 known organisms so bright that my vision was confused 

 for several seconds. Often the abundance of lights was so 

 great that the comparison was unavoidable with the major 

 stars on a clear, moonless night. The constant movement 

 tended to confuse direct, concentrated vision, but by con- 

 tinual effort I managed to follow definite, related groups of 

 lights, and in many cases could ultimately make out the 

 outline of the fish. 



Occasionally the head of a fish would appear conspicu- 

 ously against the surrounding black, illumined by some 

 unknown source of indirect lighting. Eyes especially stood 

 out with no definite source of light visible. When teeth 

 were thus silhouetted I knew it was from a luminous 

 mucus which covered them. Cheek lights flashed and 

 dimmed, or vanished altogether, showing some control 



1 "The Arcturus Adventure," pp. 214-218. 



