Luminousness of the Sea. SI I 



were of as much use seriously to refute it, as to sit down and 

 cavil with the opinion of the poet who describes the luminous 

 nature of the sea to be 



" As though the lightnings there had spent their shafts, 

 And left the fragments glittering on the field." 



It is equally unprofitable to take notice of the other 

 theories, they are all vague and unsatisfactory, they are all 

 unsupported by facts ; while the true cause, the existence of 

 animalcules, receives support and confirmation by every day*s 

 experience, and rests upon facts, numerous and easily proved. 

 Suffice it at present to say, that the animalcules have been 

 caught in the very act of giving out the luminous appearance, 

 and in vast numbers ; and that, in every instance where the 

 water has been properly examined when luminous, great 

 quantities of animalcules have been seen ; and that, on the 

 contrary, when the water has not been luminous, the animal- 

 cules have not been present, thus affording satisfactory proof 

 that they are the cause of the light so given out. 



I have already said that a considerable variety of marine 

 animals have been described and figured by authors as lumi- 

 nous. Amongst the Mollusca, the Pholas dactylus has long 

 been known to possess this property, having been described 

 as luminous by a naturalist well known in this Society, I mean 

 Pliny. Amongst the Vermes, the Nereis noctiluca is also well 

 known. Amongst the Crustacea, several species of the genera. 

 Cancer, Lynceu^, and Limulus ; and, amongst the zoophytes, 

 several species of the genera Medusa, Bero^, and Pennatula 

 have long ago been described as possessing the same property, 

 while an immense number of new genera and species have 

 been ascertained by Dr. MaccuUoch, but which have never 

 yet been published. It is with the intention, therefore, merely 

 of adding my mite to the information already acquired upon 

 this subject, and attempting to extend our knowledge with 

 regard to the species of animalcules which inhabit the sea and 

 possess a luminous quality, that I presume to offer the follow- 

 ing descriptions and remarks. 



In an excellent paper by Mr. Macartney, in the Phil. Trans. 

 1810, that gentleman describes and gives representations of a 

 considerable number of these ; and, from various observations 

 and patient research, he concludes that on our coasts, and per- 

 haps in general throughout the ocean, the luminousness of the 

 sea depends chiefly upon one species, which he denominates the 

 Medusa scintillans. During a late voyage to India and China, 

 I had various opportunities of observing the animals which 



