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contact and respiration, both internally and externally, ac- 

 quire the means of emitting this light : and, indeed, this idea, 

 which reconciles the two diverse opinions, perfectly accords 

 with the observations of Mr. Thompson, namely, that, con- 

 trary to what is observed in terrestrial animals, the aquatic 

 luminous species seem to be entirely pervaded with the light. 

 I may likewise mention another circumstance, observed by 

 the Kev. F. W. Hope, which seems to confirm this view of 

 the question, viz. that he once met with a specimen of Silpha 

 obscura upon the coast which was luminous, although the 

 species has never been observed to possess the power of 

 giving out light. In this case, the conjecture of Mr. Hope, 

 that the insect (which had evidently been feeding upon the 

 dead fish, &c., lying upon the shore in a state of decomposi- 

 tion, and about which it was crawling) had received its 

 luminosity from the putrefactive animal matter, appears to be 

 well founded. 



Moreover, in the accounts of the animalculists, we even 

 find that the presence of the animalcules is not the true and 

 only cause of the phenomenon. Mr. Baird himself tells us 

 that he put a single Medusa into a glass full of clear water, 

 and, " when taken to a dark place, the water, upon its surface 

 being struck and agitated by the finger, immediately gave 

 out several bright sparks." Now, in this case it is evident 

 that the water, and not the Medus«, gave out the light. So 

 the insect described by Riville, generally supposed to belong 

 to the genus Lynceu5, and which Miiller considers may be 

 his Lynceus brachyilrus (but, as the species of that genus 

 are only found in fresh water, it should rather belong to the 

 genus Cythere«), is not of itself luminous, but certain con- 

 glomerated globules pendent from the body are represented 

 to be so ; which Riville, indeed, supposed to be the recepta- 

 cles of phosphorescent liquid, but which Latreille, Goetze, 

 and Miiller consider as eggs. 



In concluding these observations upon the nature of the 

 luminosity of the sea, I am tempted to remark that the sup- 

 positions which have been raised as to the object of its 

 existence, appear very inapplicable thereto ; Mr. Thompson 

 considering that it may be given in order to render the dark- 

 ness and gloom less dull and irksome to the voyager, and in 

 order to diminish the number of his dangers by pointing out 

 his approach to some fatal spot ; and Mr. Baird stating that 

 the faculty of emitting light is evidently given to the animals 

 as a defence and protection, and to enable them to take their 

 prey in their deep and dark abodes. In preference to adopt- 

 ing either of these ideas, which appear to me to be " of fairy 



