FISHES. 



41.7 



Thus Nature seems to have fitted these animals with appe- 

 tites and powers of an inferior kind ; and formed tliem tor a 

 sort of passive existence in the obscure and heavy element to 

 which they are consigned. To preserve their own existence, 

 and to continue it to their posterity, fill up the whole circle of 

 their pursuits and enjoyments ; to these they are impelled rather 

 by necessity than choice, and seem mechanically excited to every 

 fruition. Their senses are incapable of making any distinc- 

 tions ; but they drive forward in pursuit of whatever they can 

 swallow, conquer, or enjoy. 



A ceaseless desire of food seems to give the ruling impulse 

 to all their motions. This appetite impels them to encounter 

 every danger ; and indeed their rapacity seems insatiable. Even 

 when taken out of the water, and almost expiring, they greedily 

 swallow the very bait by which they were allured to destruction. 



The maw is, in general, placed next the mouth, and though 

 possessed of no sensible heat, is, however, endued with a sur- 

 prising facility of digestion. Its digestive power seems, in some 

 measure, to increase with the quantity of food it is supplied 

 with ; a single pike having been known to devour a hundred 

 roaches in three days. Its faculties also are as extraordinary ; for it 

 digests not only fish, but much harder substances ; prawns, crabs, 

 and lobsters, shells and all. These the cod or the sturgeon will 

 not only devour, but dissolve down, though their shells are so 

 much harder than the sides of the stomach which contains them. 

 This amazing faculty in the cold maw of fishes, has justly ex- 

 cited the curiosity of philosophers ; and has effectually over- 

 turned the system of those who supposed that the heat of the 

 stomach was alone a sufficient instrument for digestion. Tiie 

 truth seems to be, and some experiments of the skilful Dr 

 Hunter seem to evince, that there is a power of animal assimi- 

 lation lodged in the stomach of all creatures, which we can 

 neither describe nor define, converting the substances they swal- 

 low into a fluid fitted for their own peculiar support. This 

 is done neither by trituration, nor by warmth, nor by motion, 

 nor by a dissolving tluid, nor by their united efforts; but by 

 some principle in the stomach yet unknown, which acts in a 

 different maimer from all kinds of artificial maceration. Tiie 

 meat taken into the stomach or maw is ol'tcn seen, though very 

 near being digested, still to retain its original form, and ready 



2 p 2 



