608 



A HISTORY OF 



is covered with the same transparent skin that 

 covers the rest of the head ; and which, pro- 

 bably, serves to defend it in the water, as 

 they are without eye-lids. The globe is more 

 depressed anteriorly, and is furnished behind 

 with a muscle, which serves to lengthen or 

 flatten it, according to the necessities of the 

 animal. The crystalline humour, whicli in 

 quadrupeds is flat, and of the shape of a but- 

 ton-mould, in fishes is as round as a pea; or 

 sometimes oblong, like an egg. From all this 

 it appears, that fish are extremely near-sight- 

 ed ; and that even in the water they can see 

 objects at a very small distance. This dis- 

 tance might very easily be ascertained, by 

 comparing the refraction of bodies in the wa- 

 ter, with that formed by a lens that is spheri- 

 cal. Those unskilled in mathematical calcu- 

 lations, will have a general idea of this, from 

 the glasses used by near-sighted people. 

 Those whose crystalline humour is too con- 

 vex, or, in other words, too round, are always 

 very near-sighted ; and obliged to use con- 

 cave glasses, to correct the imperfections of 

 nature. The crystalline humour offish is so 

 round, that it is not in the power of any glass- 

 es, much less of water, to correct their vision. 

 This crystalline humour in fishes all must 

 have seen; being that little hard pea-like sub- 

 stance which is found in their eyes after boil- 

 ing. In the natural state it is transparent, 

 and not much hardef*than a jelly. 



From all this it appears how far fish fall 

 behind terrestrial animals in their sensations, 

 and consequently in their enjoyments. Even 

 their brain, which is by some supposed to be 

 of a size with every animal's understanding, 

 shows that fish are inferior even to birds in 

 this particular. It is divided into three parts, 

 surrounded with a whitish froth, and gives oflf 

 nerves as well to the sense of sightas of smell- 

 ing. In some fish it is gray, in others white; 

 in some it is flatted, in others round ; but in 

 all extremely small, compared to the bulk of 

 the animal. 



Thus Nature seems to havie fitted these 

 animals with appetites and powers of an in- 

 ferior kind ; and formed them for 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 distinctions; but they drive 

 forward in pursuit of whatever they can swal- 

 low, 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 dan- 

 ger; and indeed their rapacity seems insa- 

 tiable. 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 surprising 

 faculty of digestion. Its digestive power seems, 

 in some measure, to increase with the quan- 

 tity *o 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 dis- 

 solve 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 excited the cu- 

 riosity of philosophers ; and has effectually 

 overturned the system of those, who supposed 

 that the heat of the stomach was alone a suffi- 

 cient instrument for digestion. The truth 

 seems to be, and some experiments of the 

 skilful Dr. Hunter seem to evince, that there 

 is a power of animal assimilation lodged 

 in the stomach of all creatures, which we can 

 neither describe nor define, converting the 

 substances they swallow 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 fluid, nor by their 

 united efforts; but by some principle in the 

 stomach yet unknown, which acts in a differ- 

 ent manner from all kinds of artificial mace- 

 ration. The meat taken into the stomach or 

 maw is often seen, though very near being 

 digested, still to retain its original form : and 

 ready for a total dissolution, while it appears 

 to the eye as yet untouched by the force of 



