CLASS IV. PISCES. 255 



any apparent sustenance; and even the pike, the most 

 voracious, will exist in a pond wholly by itself. 



Fishes that have small mouths feed on worms, and the 

 spawn of their own tribes ; but those which have large 

 mouths pursue any thing which they are capable of over- 

 powering, and frequently meet each other in fierce oppo- 

 sition. Indeed the life of fishes, from the smallest to the 

 greatest, is but one continual scene of hostility, violence, 

 and evasion. Some make annual migrations from one part 

 of the ocean to another, in pursuit of food, or to find a 

 situation more congenial to their nature. In general they 

 seem averse to very cold water ; and either seek a warmer 

 atmosphere or the shallows on their native coasts, which 

 are susceptible of the influence of the sun. 



Though all the various tribes live in water, yet they all 

 require the assistance of air. When a fish is in the water, 

 it is easy to observe the motion of its lips and gills, which 

 is unquestionably analagous to our breathing. They have 

 also a receptacle called the air-bladder, or swim ; which, 

 though it assists the animal in rising or sinking, is also the 

 storehouse of air, from which it draws supplies according 

 to its exigencies. 



" Most of the disorders," says Bacon, " to which man- 

 kind are subject, arise from the changes and alterations of 

 the atmosphere ;" and if fishes are limited in their other en- 

 joyments, they reside in an element little liable to varia- 

 tion, and therefore are exempted from numerous maladies. 

 They indeed pass a uniform existence ; their movements 

 are without effort, and their lives without labour. If they 

 escape the dangers of their situation, it is impossible feo 

 say what bounds are placed to their size or age. Various 

 methods have been imagined to ascertain their duration, 

 but none that can be altogether relied upon. It is highly 

 probable that they reach extraordinary longevity; but 

 still their fecundity is more astonishing. Some produce 

 their young alive, and others only eggs ; the former are 

 the least prolific, yet the viviparous blenny will bring forth 

 two or three hundred at a time. Such as exclude their 

 progeny in eggs are obliged to leave them to chance at 



