FIXED LUMINARIES OF THE SEA. 23 



caused by the disturbance they made in passing through the immense 

 shoal of coral polyps. The sight was curious and interesting; it had 

 the appearance of an immense meteor coming directly down on our boat, 

 as they were all heading for the entrance of the harbor where we lay. 

 The bows of the fishing-boats made a great disturbance as they struck 

 them, and the luminosity was most intense; but, as the waves were 

 thrown off from the bows at a wide angle, the disturbance continued, 

 and the colored light from the little creatures formed a long streak from 

 behind the boat, representing the head of a comet with a long tail. 

 Imagine twenty or thirty of these boats all heading in one direction, and 

 you may form a faint idea of the scene. The polyps were not alone, but 

 larger animals were darting and gyrating about, sending out 'vivid streaks 

 of light. 



The phosphorescent light of these polyps is probably the effect of a 

 vital action ; it appears as a single spark, like that of various insects, 

 and is repeated at short intervals. 



In 1867 I passed through a belt of dark-colored water in a large 

 stream. It had been observed from the masthead for sometime before 

 we reached it : it proved to be a belt, of miles in extent, composed of 

 animalcules. When taken up in a bucket, they gave out the strongest 

 phosphorescent light I have ever witnessed. It required the highest 

 power of my microscope to define them, and they were of many species 

 new to me. Our steamer, a side-wheel vessel, made a great commotion 

 as we passed for hours through this belt of living matter. These belts 

 or patches, covering vast tracts of the ocean, are not uncommon. They 

 are often seen in the Indian Ocean after severe storms and hurricanes. 

 They vary in color. I have seen them of olive green, of a yellowish tint, 

 and often a dark blue. Once, after a spent hurricane at Mauritius, I 

 passed through a belt three miles wide, of a deep purple, so much so it 

 could be seen a long way from shore. 



Giglioli, the Italian naturalist, refers to the phosphores- 

 cence of madreporic polyps as being quite different from 

 that of other forms. He observed on the coast of Sumatra 

 and Batavia, that, when the bottom of his launch grounded 



