FISHES IN GENERAL. 289 



I*ole. The cod from the banks of Newfoundland pur- 

 sue the whiting, which flies before it, to the most 

 southern shores of Spain ; and the cacherlot is said to 

 follow shoals of herrings, and to swallow thousands at 

 a single gulp. This may be one cause of their annual 

 migration, though others likewise may be produced : 

 they may change their residence for one more suited to 

 their constitution, or more adapted for depositing their 

 spawn. 



It is remarkable that no fish are fond of very cold 

 waters, and in summer are seen in numbers lying in 

 shallows near the shore, where the sun has the power 

 of warming the water to the bottom ; and, in the win- 

 ter, to the lowest depths of the ocean, where the cold- 

 ness of the atmosphere has not the power to reach. 



The severity of the winter is fatal to many fresh-water 

 fish, as may frequently be observed after the break- 

 ing up of a frost : this is often occasioned by the air 

 being excluded from them by the thick impenetrability 

 of the sheets of ice. Though all fish reside in the 

 water, air is necessary to the preservation of their lives; 

 yet nothing is more difficult to be accounted for, tnau 

 the manner in which they obtain the supply. The use 

 that is generally assigned to the air-bladder, is the en- 

 abling the fish to rise or sink at its will ; but the An- 

 cients were of opinion that it was to come in aid of the 

 lungs, and to remain as a kind of storehouse of air to 

 supply the animal, if distressed ; and to this opinion we 

 are inclined to assent. 



Hitherto We have seen the inhabitants of the ocean 

 every way inferior to those which dwell upon the land ; 

 but, if they are capable of fewer enjoyments, they are 

 generally endowed with a greater length of life ; for, 

 residing in an element subject to but little variation, 



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