OBSERTAXIONS ON LUMINOUS ANIMALS* 3/]^'J 



chaias thus formed did not exceed three inches in length, 

 and emitted a pale phosphoric light. By introducing his 

 hand into the water, Mr. LangstafF raised upon it several 

 chains of the luminous globules; which were separated by 

 opening the fingers, but readily reunited on being brougiit 

 again into contact, like globules of quicksilver. The glo- 

 bules, he says, wer*^ so transparent, that they could not be 

 perceived when the hand was taken into the light. 



This extraordinary appearance of the sea was visible for which comi- 

 two nights. As soon as the moon exerted her influence, ^[Jfj^j^'^'j^^j^^ 

 the sea changed to its natural dark colour, and exhibited was di-sipated 

 distinct glittering points, as at other times. The pheno- j-Lj^^ nioon- 

 menon, he says, had never been witnessed before by any 

 ef the company on board, /although some of the crew had 

 been two or three times round the globe. 



I consider this account of Mr. Langstaff very interesting 

 and important, as it proves, that the diffused light of the 

 sea is produced by an assemblage of minute mednsa; on the 

 surface of the water. 



In June 1806, I found the sea at Margate more richly Number of the 



stored with the small luminous medusa, than I have ever^"~'^'""™'"°"* 



' . ntediT^K caught 



seen it. A bucket of the water being set by for some at Margate. 



time, the animaJs sought the surface, and kept up a con- 

 tinual sparkling, which must have been occasioned by the 

 motions of individuals, as the water was perfectly at rest. 

 A small quantity of the lunvinous water was put into a 

 glass jar, and on standing some time, the medusce collected - ' 



at the top of the jar, and formed a gelatinous mass, one 

 inch and a half thick, and of a reddish or mud colour, 

 leaving the water underneath perfectly clear. 



In order to ascertain if these; animals would materially They did not 

 alter their size, or assume the figure of any other known ^J^j''*^'^"^'^^^^ 

 species of medusa, I kept them alive for 23 days, by their size ia 

 carefully changing the water in which they were placed ; "^ '^^■'^' 

 during which time, although they appeared as vigorous as 

 ■when first taken, their form was not in the slightest degree 

 altered, and their size but little increased. By this cxperi.; 

 mcnt I was confirmed in the opinion of their being a distinct 

 species, as the young actinia; and medusa; exhibit the form 

 of tlje parent in a much shorter period than the above. 

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