108 THE STORY OF LIFE IN THE SEAS. 



tinguished. In the Malay Archipelago several 

 of these bright lights may be seen near the sur- 

 face of the water on calm mornings just before 

 sunrise, and it is extremely interesting to watch 

 them gradually sinking down into deeper water 

 as the day dawns, and then suddenly going out 

 one after the other. 



Some of the large Jelly-fishes, such as Pelagia 

 noctiluca, glow with a soft blue light. The curious 

 pelagic Tunicate colony Pyrosorm receives its 

 name from the fact that it emits a bright light. 

 A giant Pryosoma was caught by the Challenger 

 in the deep-sea trawl, and, to quote the words of 

 Professor Moseley once more, "It was like a 

 great sac, with walls of jelly about an inch in thick- 

 ness. It was four feet in length and ten inches 

 in diameter. When a Pyrosoma is stimulated by 

 having its surface touched, the phosphorescent 

 light breaks out at first at the spot stimulated, 

 and then spreads over the surface of the colony 

 as the stimulus is transmitted to the surrounding 

 aninlals. I wrote my name with my finger on 

 the surface of the giant Pyrosoma as it lay in a 

 tub at night, and the name came out in a few 

 seconds in letters of fire." 



All of these animals are sufficiently large to be 

 easily seen by the naked eye, and the phenomena 

 of their phosphorescence can be carefully ob- 

 served. But many of the more minute forms of 

 life also exhibit this peculiarity, and contribute 

 in no small degree to the bright light of the sea. 



For instance, when the sea on our coasts 

 shows a dull blue light, flashing into greater in- 

 tensity where the ripples break, it will be found 



