JURA. LUMINOUS ANIMALS. 201 



during the darkness of night in our more shallow seas, 

 should be enabled to discover their food without the 

 aid of light, which even in these minor depths must 

 entirely disappear during the night. To supply this 

 want, the property of phosphorescence seems to have 

 been conferred on this class of animals, and apparently, 

 in the greatest degree on those whose astonishing powers 

 of reproduction, and whose insensibility, nearly approach- 

 ing to vegetable life, seem to mark them as having been 

 principally created for the supply of the more perfect 

 tribes. In these also, as well as in the larger fishes, 

 the phosphorescent property may serve for enabling them 

 to pursue their own prey as well as for disclosing them- 

 selves to their pursuers. 



The economy of the northern whale is in some degree 

 connected with this subject, and seems to add a further 

 proof of the truth of the views here held out. In the 

 latitudes which this animal inhabits, it can often have 

 no guide but the light of its prey or that of its own 

 body ; although the occupations of the whale fishers 

 during the summer, in the time of perpetual light, do not 

 permit them to observe the luminous appearance of the 

 water, and we are unacquainted with these regions during 

 the darkness of the polar winter. But the great depth 

 of the sea which it frequents, as determined by the obser- 

 vations of the recent navigator above mentioned, toge- 

 ther with the circumstance of its well known food being 

 found at the bottom as well as at the top of that sea, 

 are sufficient to prove that even in summer it must occa- 

 sionally feed in regions inaccessible to light. 



I may add to these general remarks, that the luminous 

 property of dead fish, is perhaps calculated for similar wise 

 ends to those already mentioned. These, sinking to the 

 bottom of the ocean, become capable of attracting the 

 attention of the deep-water fishes ; answering the double 

 purpose, of food to these tribes, and admitting the re- 

 moval, as in the air, of carcases which might produce, 



