No. 3.] PHOSPHORESCENT ORGANS. 6S5 



bers are beyond doubt true phosphorescent organs, as the 

 following observations will demonstrate. 



A live fish put into an aquarium of seawater made alkaline 

 with ammonia water, exhibited a most brilliant glow along the 

 location of the well-developed organs. Not only did the lines 

 of organs shine forth, but the individual organs themselves 

 were distinguishable. The glow appeared after about five 

 minutes, remained prominent for a few minutes, and then for 

 twenty minutes gradually became weaker until it was scarcely 

 perceptible. Rubbing the hand over the organs was followed 

 always by a distinct increase in the phosphorescence. Pieces 

 of the fish containing the organs taken five and six hours after 

 the death of the animal became luminous upon treatment with 

 ammonia water. 



Electrical stimulation of the live fish was also tried with 

 good success. The interrupted current from an induction coil 

 was used, one electrode being fixed on the head over the brain 

 or on the exposed spinal cord near the brain, and the other 

 moved around on different parts of the body. No results fol- 

 lowed relatively weak stimulation of the fish, although such 

 currents produced violent contractions of the muscular system 

 of the body. But when a current strong enough to be quite 

 painful to the hands while handling the electrodes was used, 

 then stimulation of the fish called forth a brilliant glow of light 

 from apparently every well-developed organ in the body. All 

 the lines on the ventral and lateral surfaces of the body glowed 

 with a beautiful light, and continued to do so while the stimu- 

 lation lasted. The single well-developed organ just back of 

 and below the eye was especially prominent. No luminosity 

 was observed in the region of the dorsal organs previously 

 described as rudimentary in structure. I was also able to 

 produce the same effect by galvanic stimulation, rapidly making 

 and breaking the current by hand. 



The light produced in Porichthys was, as near as could be 

 determined by direct observation, a white light. When pro- 

 duced by electrical stimulation it did not suddenly reach its 

 maximal intensity, but came in quite gradually and disappeared 

 in the same way when the stimulation ceased. The light was 



