4)6 TRAVELS IN BRAZIL. 



the surface of the water in long yellowish brown 

 stripes, and looked like a stream covered with saw- 

 dust. This, however, is never seen except when 

 the sky is covered with thick clouds, which darken 

 the sea. These marine infusoria appear to avoid 

 the light of the sun, and to sink in the daytime to 

 the bottom, to return to the surface as soon as 

 darkness sets in ; at least they were not to be found 

 in the water which was taken up in the daytime, 

 but only in that which we took up at night. The 

 mode of life and the social instinct which the above- 

 mentioned little arethusas have in common with 

 the other zoophytes, salpae, &c. may perhaps be 

 the cause that they are met with very frequently in 

 some parts of the sea, and in others very rarely, or 

 not at all. In the bay of Gibraltar they were so 

 abundant, that if we only dipped a hand in the water, 

 a furrow of light was immediately seen, and the hand 

 when taken out shone in innumerable points. 

 All these facts seem therefore to prove that the 

 phosphorescence of the sea is principally to be 

 attributed to animals. The large fiery balls, often 

 a foot in diameter, which rise singly above the 

 water, or swim about in it, are probably larger 

 mollusca or medusae, or perhaps bladders in the 

 water, illumined by the phosphoric light of these 

 animals. But, besides this insulated or sparkling 

 phosphorescence, there is another, the natural 

 characteristics of which seem not to have been yet 

 sufficiently distinguished. At some distance from the 



