FISHES. 231 



reaching to such a depth and lower beneath it, no 

 longer offers, or at least scarcely offers, to the ob- 

 server on the deep sea lead, aught except broken 

 shells, teeth of fish, sand, and rock. No nets ex- 

 ceeding half that depth are anywhere in use, and 

 the fish which are sometimes caught at fifty fathoms 

 below the surface, are in general of species provided 

 with eyes of such magnitude as to indicate the proba- 

 bility, that their enlarged organs of vision are neces- 

 sary in a medium so dense and remote from the 

 light. Besides it may be asked for what purpose 

 fishes would descend, to depths where the action of 

 their respiratory organs must be affected by the 

 diminished quantity of air, if it were not to feed 

 upon the ultimate beds of shell fish, which also could 

 neither exist nor multiply if they were below the 

 limits of light. For light, the manifestation of solar 

 action, is necessary in a greater or less degree ; 

 diurnally or at greater intervals ; to the whole of 

 organic nature.^ The species therefore which peri- 

 odically rise from the deep, and after a space return 



* As within the higher strata of the atmosphere life cannot be 

 sustained for any prolonged period, so below the surface of 

 the sea, at a depth where the density of the mass exceeds certain 

 limits it is equally improbable that animated beings can exist. 

 Coral animals are now known not to raise their stony habitations 

 from the vast depths once assigned to them ; nor do we know of 

 a well authenticated fact, establishing the existence of beds of 

 shell fish (mollusca) so low down as one hundred and fifty fa- 

 thoms of water. But at the depths where these lie and multiply, 

 the gregarious species of fish and in particular the gadoid genera 

 are known to arrive periodically to feed upon this living herb- 

 age of the submarine floor for a given season, and not constantly, 

 for that would exhaust the supply of food never again to be 

 restored. Hither the shoals which come to feed are followed by 

 more daring and more powerful enemies, for a period hanging 

 on their flanks or mixed with the migratory tribes, to devour them 

 in their turn. To guide the larger genera it appears that smaller 

 species of the same family precede them, who are in their turn 

 preceded by cephalopodes and other lower animals, each attract- 

 ing the other and annualy passing over the same geographical 

 space to perform the duties of their destiny. On the Banks of 



