234 
NATURAL HISTORY OF SELBORNE. 
of the water with its belly uppermost. The reason why fishes, 
when dead, swim in that manner is very obvious ; because, when 
the body is no longer balanced by the fins of the belly, the broad 
muscular back preponderates by its own gravity, and turns the 
belly uppermost, as lighter from its being a cavity, and because 
it contains the swimming-bladders, which contribute to render it 
buoyant * Some that dehght in gold and silver fishes have 
adopted a notion that they need no aliment. True it is that they 
vrill subsist for a long time without any apparent food but what 
they can collect from pure water frequently changed ; yet they 
must draw some support from animalcula, and other nourish- 
ment supplied by the water ; because, though they seem to eat 
nothing, yet the consequences of eating often drop from them. 
That they are best pleasied with such jejune diet may easily be 
confuted, since if you toss them crumbs they will seize them 
with great readiness, not to say greediness : however, bread 
should be given sparingly, lest, turning sour, it corrupt the 
water. They will also feed on the water-plant called lemna 
(duck^s meat), and also on small fry. 
When they want to move a little they gently protrude them- 
selves with their pinncB pectorales ; but it is with their strong 
muscular tails only that they and all fishes shoot along with such 
inconceivable rapidity. It has been said that the eyes of fishes 
are immoveable: but these apparently turn them forward or 
backward in their sockets as their occasions require. They take 
little notice of a lighted candle, though applied close to their 
heads, but flounce and seem much frightened by a sudden stroke 
of the hand against the support whereon the bowl is hung ; 
especially when they have been motionless, and are perhaps 
asleep. As fishes have no eyelids, it is not easy to discern when 
they are sleeping or not, because their eyes are always open. 
Nothing can be more amusing than a glass bowl containing 
such fishes : the double refractions of the glass and water repre- 
sent them, when moving, in a shifting and changeable variety of 
dimensions, shades, and colours; while the two mediums, as- 
sisted by the concavo-convex shape of the vessel, magnify and 
distort them vastly; not to mention that the introduction of 
* The uses of the swimming bladder of fish are at present not in the least understood, though 
many naturalists have taken great pains to investigate the subject. It is wanting, or rather (to 
express it better) it is not present, in many species, even in some which are closely allied to those 
which have it. Thus, it is not found in the common mackarel, while it exists in its near congener 
the Spanish mackarel, a species comparatively rare in the British seas. — £o. 
