122 EMISSION OF LIGHT 



has been remarked to emit phosphoric light at cer- 

 tain seasons of the year.* 



Among the Khizopodes, the species named by 

 Ehrenberg Mammaria scintillans, now better 

 known as Noctiluca miliaris, which is never larger 

 than the head of a small pin according to Hum- 

 boldt (I never saw one half so large), " offers to 

 the microscopical investigator of Nature, the mag- 

 nificent spectacle of a starry firmament reflected 

 in the sea." Humboldt tells us, in one of his 

 works, that his body has remained luminous for 

 an hour together, covered as it was by Noctiluca, 

 after bathing in the waters of the Pacific. 



Noctiluca miliaris is very common in the Eng- 

 lish Channel ; and I have found this species in such 

 prodigious numbers in the damp sand at Ostend, 

 that on raising a handful of it, it appeared like so 

 much molten lava. 



In the year 1854, the number of marine animals 

 known to be endowed with phosphorescent pro- 

 perties during life, amounted to upwards of a 

 hundred distinct species, all invertebrata. 



MM. Edoux and Soulezet, two French natu- 



* It would certainly be interesting to introduce some of these 

 luminous animals into the marine aquariums which are much 

 in vogue at present. For my own part, I have often been de- 

 lighted with the phosphorescent spectacle some of them present in 

 a small flask. The species figured in the text are perhaps among 

 the more worthy of notice in this respect, viz. fig. 19, Thaumantius 

 pilosella; fig. 21, ^Cydippe pileus ; fig. 22, Beroe Forskallii, etc. 



