334 SUMMARY AND CONCLUSIONS 



The most important fact in bathysphere work at the 

 greatest depths is to keep the eyes dark adapted. This was 

 constantly attested both by my own difficulties in seeing 

 and identifying, and by those of Barton and Tee- Van. 

 Mr. Barton's photographic efforts at the deepest levels 

 required frequent use of the 1500 watt light, speeded up to 

 125 volts, which lighted up the whole interior of the 

 sphere, of magnesium flash bulbs, and of ordinary hand 

 flash-lights. One magnesium bulb which went off in front 

 of Barton's face blinded him for many hundred feet, 

 showing how complete was the darkness in the interludes 

 of illumination. 



Although he came to the window, in his own words 

 "hundreds of times" whenever I saw anything of unusual 

 interest, he missed many of the organisms which I dis- 

 tinguished, due apparently to the frequent use of the 

 various sources of interior illumination, as well as to divided 

 interest between observation and photography. Mr. Tee- 

 Van, who sat in Barton's place during one 1500 foot dive, 

 saw quite as much as I did, as we did away with all illumi- 

 nation and concentrated on the windows every possible 

 second. I found that even a momentary distraction, like 

 examining the instruments, diminished my visual powers 

 for a few minutes, very considerably. 



There was a decided dazzling power in the larger organic 

 flashes, and the sudden emanation of shrimp luminosity 

 startled one by its unexpectedness. Yet the immediate 

 vicinity of sustained animal illumination was never wholly 



