24 VIEWS OP THE MICROSCOPIC WORLD. 



instance, similar kinds are found at the heads of rivers where the water is fresh, 

 and their mouths, where the streams mingle with the briny ocean. 



If sea-water, abounding with marine animalcules, is mixed by slow degrees with 

 the fluid in which fresh-water species reside, the latter survive ; but if the mixture 

 is suddenly made, they perish immediately. 



PHOSPHORESCENCE OF THE SEA. Various opinions have at times been entertained 

 in respect to the cause of this beautiful phenomena; but it is now correctly attrib- 

 uted chiefly to the presence of animalcules, which crowd the waters in vast 

 multitudes. This appearance, although confined to no particular part of the ocean, 

 attains its greatest splendor in the tropical climes, where the spectacle is often 

 exceedingly grand and beautiful. 



This brilliant phenomenon is thus graphically described by Darwin in his 

 " Voyage of a Naturalist:" "While sailing a little south of the River La Plata, 

 on one very dark night, the sea presented a wonderful and most beautiful spectacle. 

 There was a iresh breeze, and every part of the surface, which, during the day, is 

 seen as foam, now glowed with a pale light. The vessel drove before her bows two 

 billows of liquid phosphorus, and in her wake she was followed by a milky train. 

 As far as the eye reached, the crest of every wave was bright, and the sky above 

 the horizon, from the reflected glare of these livid flames, was not so utterly ob- 

 scure as over the vault of the heavens. Near the mouth of the Plata some circular 

 and oval patches, from two to four yards in diameter, shone with a steady but 

 pale light, while the surrounding water only gave out a few sparks. The appear- 

 ance resembled the reflection of the moon, or some luminous body, for the edges 

 were sinuous from the undulations of the surface. The ship, which drew thirteen 

 feet of water, passed over without disturbing these patches ; we must therefore 

 suppose that some of the luminous marine animals were congregated together at 

 a greater depth than the bottom of the vessel, or thirteen feet beneath the surface 

 of the sea." 



The same phenomenon is thus depicted in the glowing language of Colton : 

 u We had last night a splendid exhibition of aquatic fire-works. The night was 

 perfectly dark, arid the sea smooth, and you might see a thousand living rockets 

 shooting in all directions from our ship, and running through countless configura- 

 tions, return to her, leaving their track still bright with unextinguishable flame. 

 Then they would start again, whirling through every possible gyration, till the 

 whole ocean around seemed medallioned with fire. We had run into an immense 

 shoal of porpoises and small fish ; the sea being filled at the same time with ani- 

 malculae, which emit a bright phosphoric light when the water is agitated. The 

 chase of the porpoises after these small fish created the beautiful phenomenon de- 

 scribed. The light was so strong that you could see the fish with the utmost dis- 

 tinctness. They lit their own path like a sky-rocket in a dark night; and our ship 

 left the track of its keel in the wave for half a mile. I have witnessed the illumi- 

 nation of St. Peter's, and the castle of St. Angelo, at Rome, and heard the shout 

 of the vast multitudes as the splendors broke over the dark cope of night, but no 

 pyrotechnic displays ever got up by human skill could rival the exhibitions of 

 nature around our ship." That the cause of this brilliant phenomenon is correctly 

 assigned to marine animals has been proved by the examination of the luminous 

 water, for if it is placed in a tumbler and agitated, they immediately emit light in 



