Abbildungen der Seite
PDF

200. In Studying The Conformation Of Fishes, we naturally conclude that they are, in every respect, well adapted to the element in which they have their existence. Their shape has a striking resemblance to the lower part of a ship; and there is no doubt that the form of the fish originally suggested the form of the ship. The body is in general slender, gradually diminishing towards each of its extremities, and flattened on each of its sides. This is precisely the form of the lower part of the hull of a ship; and it enables both the animal and the vessel, with comparative ease, to penetrate and divide the resisting medium for which they have been adapted. The velocity of a ship, however, in sailing before the wind, is by no means to be compared to that of a fish. It is well known that the largest fishes will, with the greatest ease, overtake a ship in full sail, play round it without effort, and shoot ahead of it at pleasure. This arises from their great flexibility, which, to compete with mocks the labours of art, and enables them to migrate thousands of miles in a season, without the slightest indications of languor or fatigue.

201. The Principal Instruments Empeoted Bt Fishes to accelerate their motion, are their air-bladder, fins, and tail. By means of the air-bladder they enlarge or diminish the specific gravity of their bodies. When they wish to sink, they compress the muscles of the abdomen, and eject the air contained in. it; by which, their weight, compared with that of the water, is increased, and they consequently descend. On the other hand, when they wish to rise, they relax the compression of the abdominal muscles, when the air-bladder fills and distends, and the body immediately ascends to the surface. How simply, yet how wonderfully, has the Supreme Being adapted certain means to the attainment of certain ends! Those fishes which are destitute of the air-bladder are heavy in the water, and have no great "alacrity" in rising. The larger proportion of them remain at the bottom, unless they are so formed as to be able to strike their native element downwards with sufficient force to enable them to ascend. When the air-bladder of a fish is burst, its power of ascending to the surface has for ever passed away. From a knowledge of this fact, the fishermen of cod are enabled to preserve them alive for a considerable time in their well-boats. The means they adopt to accomplish this, is to perforate the sound, or air-bladder, with a needle, whioh disengages the air, when the fishes immediately descend to the bottom of the well, into which they are thrown. Without this operation, it would be impossible to keep the cod under water whilst they had life. In swimming, the fins enable fishes to preserve their upright position, especially those of the belly, which act like two feet. Without these, they would swim with their bellies upward, as it is in their backs that the centre of gravity lies. In ascending and descending, these are likewise of great assistance, as they contract and expand accordingly. The tail is an instrument of great muscular force, and largely assists the fish in all its motions. In some instances it acts like the rudder of a ship, and enables it to turn sideways; and when moved from side to side with a quick vibratory motion, fishes are made, in the same manner as the "screw" propeller makes a steamship, to dart forward with a celerity proportioned to the muscular force with which it is employed.

202. The Bodies or Fishes are mostly covered with a kind of horny scales; but some are almost entirely without them, or have them so minute as to be almost invisible ; as is the case with the eel. The object of these is to preserve them from injury by the pressure of the water, or the sudden contact with pebbles, rocks, or sea-weeds. Others, again, are enveloped in a fatty, oleaginous substance, also intended as a defence against the friction of the water; and those in which the scales are small, are supplied with B larger quantity of slimy matter.

203. The Respiration Of Fishes is effected by means of those comb-Iiko organs which are placed on each side of the neck, and which are called gills. It is curious to watch the process of breathing as it is performed by the finny tribes. It seems to be so continuous, that it might almost pass for an illustration of the vexed problem which conceals the secret of perpetual motion. In performing it, they fill their mouths with water, which they drive backwards with a force so great as to open the large flap, to allow it to escape behind. In this operation all, or a great portion, of the air contained in the water, is left among the leather-like processes of the gills, and is carried into the body, there to perform its part in the animal economy. In proof of this, it has been ascertained that, if the water in which fishes are put, is, by any means, denuded of its air, they immediately seek the surface, and begin to gasp for it. Hence, distilled water is to them what a vacuum made by an air-pump, is to most other animals. For this reason, when a fishpond, or other aqueous receptacle in which fishes are kept, is entirely frozen over, it is necessary to make holes in the ice, not so especially for the purpose of feeding them, as for that of giving them air to breathe.

204. The Positions Of The Teeth Of Fishes are well calculated to excite our amazement; for, in some cases, these are situated in the jaws, sometimes on the tongue or palate, and sometimes even in the throat. They are in general sharp-pointed and immovable; but in the carp they are obtuse, and in the pike so easily moved as to seem to have no deeper hold than such as tho mere skin can afford. In the herring, the tongue is set with teeth, to enable it the better, it is supposed, to retain its food.

205. Although Naturalists Have Divided Fishes into two great tribes-, the osseous and the cartilaginous, yet the distinction is not very precise ; for the first have a great deal of cartilage, and the second, at any rate, a portion of calcareous matter in their bones. It may, therefore, be said that the bones of fishes form a kind of intermediate substance between true bones and cartilages. The backbone extends through the whole length of the body, and consists of Arm strong and thick towards the head, but weaker and more slender as it approaches the tail. Each species has a determinate number of vertebrae, which are increased in size in proportion with the body. The ribs are attached to the processes of the vertebrae, and inclose the breast and abdomen. Some kinds, as the rays, have no ribs; whilst others, as the sturgeon and eel, have very short ones. Between the pointed processes of the vertebra are situated the bones which support the dorsal (back) and the anal (below the tail) fins, which are connected with the processes by a ligament. At the breast are the sternum or breastbone, clavicle or collar-bones, and the scapula or shoulderblades, on which the pectoral or breast fins are placed. The bones which support the ventral or belly fins are called the ossa pelvis. Besides these principal bones, there are often other smaller ones, placed between che mascies to assist their motion.

106. Some Of The Organ3 Op Sense In Fishes are supposed to bo possessed by them in a high degree, and others much more imperfectly. Of the latter kind are the senses of touch and taste, which are believed to be very slightly developed: On the other hand, those of hearing, seeing, and smelling, are ascertained to be acute, but the first in a lesser degree than both tho second and third. Their possession of an auditory organ was long doubted, and even denied by some physiologists; but it has been found placed on the sides of the skull, or in the cavity which contains the brain. It occupies a position entirely distinct and detached from the skull, and, in this respect, differs in tho local disposition of the same sense in birds and quadrupeds. In some fishes, as in those of the ray kind, the organ is wholly encompassed by those parts which contain the cavity of the skull; whilst in the cod and salmon kind it is in the part within the skull. Its structure is, in every way, much more simplo than that of the same sense in those animals which live entirely in the air; but there is no doubt that they have the adaptation suitable to their condition. In some genera, as in the rays, the external orifice or ear is very small, and is placed in the upper surface of the head; whilst in others there is no visible externa.} orifice whatever. However perfect the sight of fishes may be, experience has shown that this sense is of much less use to them than that of smelling, in searching for their food. The optic nerves in fishes have this peculiarity,—that they are not confounded with one another in their middle progress between their origin and their orbit. The one passes over the other without any communication ; so that the nerve which comes from the left side of the brain goes distinctly to the right eye, and that which comes from the right goes distinctly to the left. In the greater part of them, the eye is covered with the same transparent skin that covers the rest of the head. The object of this arrangement, perhaps, is to defend it from the action of the water, as there are no eyelids. The globe in front is somewhat depressed, and is furnished behind with a muscle, which serves to lengthen or flatten it, according to the necessityties of the animal. The crystalline humour, which in quadrupeds is flattened, is, in fishes, nearly globular. The organ of smelling in fishes is large, and is endued, at its entry, with a dilating and contracting power, which is employed as the wants of the animal may require. It is mostly by the acuteness of their smell that fishes are enabled to discover their tood; for their tongue is not designed for nice sensation, being of too firm a cartilaginous substance for this purpose.

207. With Respect To The Food Op Fishes, this is almost universally found in their own element. They are mostly carnivorous, though they seize upon almost anything that comes in their way : they even devour their own offspring, and manifest a particular predilection for all living creatures. Those, to which Nature has meted out mouths of the greatest capacity, would seem to pursue everything with life, and frequently engage in fierce conflicts with their prey. The animal with the largest mouth is usually the victor; and he has no sooner conquered his foe than he devours him. Innumerable shoals of one species pursue those of another, with a ferocity which draws them from the pole to the equator, through all the varying temperatures and depths of their boundless domain. In these pursuits a scene of universal violence is the result; and many species must have become extinct, had not Nature accurately proportioned the means of escape, the production, and the numbers, to the extent and variety of the danger to which they are exposed. Hence the smaller species are not only more numerous, but more productive than the larger; whilst their instinct leads them in search of food and safety near the shores, where, from the shallowness of the waters, many of their foes are unable to follow them.

I

208. The Fecundity Op Fishes has been the wonder of every natural philosopher whose attention has been attracted to the subject. They are in general oviparous, or egg-producing; but there are a few, such as the eel and the blenny, which are viviparous, or produce their young alive. The males have the milt and the females the roe; but some individuals, as the sturgeon and the cod tribes, are said to contain both. The greater number deposit their spawn in the sand or gravel; but some of those which dwell in the depths of tho ocean attach their eggs to sea-weeds. In every instance, however, their fruitfulness far surpasses that of any other race of animals. According to Lowenhoeck, the cod annually spawns upwards of nine millions of eggs, contained in a single roe. The flounder produces one million ; the mackerel above five hundred thousand; a herring of a moderate size at least ten thousand; a carp fourteen inches in length, according to Petit, contained two hundred and sixty-two thousand two hundred and twenty-four; a perch deposited three hundred and eighty thousand six hundred and forty; and a female sturgeon seven millions six hundred and fifty-three thousand two hundred. The viviparous species are by no means so prolific ; yet the blenny brings forth two or three hundred at a time, which commence sporting together round their parent the moment they have come into existence.

209. In Reference To The Longevity Op Fishes, it is affirmed to surpass that of all other created beings ; and it is supposed they are, to a great extent, exempted from the diseases to which the flesh of other animals is heir. In place of suffering from the rigidity of age, which is tho cause of the natural decay of those that " live and move and have their being" on the land, their bodies continue to grow with each succeeding supply of food, and the conduits of life to perform their functions unimpaired. The age of fishes has not been properly ascertained, although it is believed that the most minute of the species has a longer lease of life than man. The mode in which they die has been noted by the Rev. Mr. White, the eminent naturalist of Selbourne. As soon as the fish sickens, the head sinks lower and lower, till the animal, as it were, stands upon it. After this, as it becomes weaker, it loses its poise, till the tail turns over, when it comes to the surface, and floats with its belly upwards. The reason for its floating in this manner is on account of the body being no longer balanced by the fins of the belly, and the broad muscular back preponderating, by its own gravity, over the belly, from this latter being a cavity, and consequently lighter.

2io. Fishes Are Either Solitary Or Gregarious, and some of them migrate to great distances, and into certain rivers, to deposit their spawn. Of sea-fishes, the cod, herring, mackerel, and many others, assemble in immense shoals, and migrate through different tracts of the ocean; but, whether considered in their solitary or gregarious capacity, they are alike wonderful to all who look through Nature up to Nature's God, and consider, with due humility, yet exalted admiration, the sublime variety, beauty, power, and grandeur of His productions, as manifested in the Creation.

FISH AS AN ARTICLE OP HUMAN FOOD.

ill. As The Nutritive Properties Of Fish are deemed inferior to those

of what is called butchers' meat, it would appear, from all we can learn, that,

in all ages, it has held only a secondary place in the estimation of those who

have considered the science of gastronomy as a large element in the happiness

of mankind. Among the Jews of old it was very little used, although it seems

not to have been entirely interdicted, as Moses prohibited only the use of such

as had neither scales nor fins. The Egyptians, however, made fish an article

of diet, notwithstanding that it was rejected by their priests. Egypt, however,

is not a country favourable to the production of fish, although we read of the

people, when hungry, eating it raw; of epicures among them having dried it

in the sun ; and of its being salted and preserved, to serve as a repast on days

of great solemnity.

The modern Egyptians are, in general, extremely temperate in regard to food. Even the richest among them take little pride, and, perhaps, experience as little delight, in the luxuries of the table. Their dishes mostly consist of pilafs, soups, and stews, prepared principally of onions, cucumbers, and other cold vegetables, mixed with a little meat cut into small pieces. On special occasions, however, a whole sheep is placed on the festive board; but during several of the hottest months of the year, the richest restrict themselves entirely to a vegetable diet. The poor are contented with a little oil or sour milk, in which they may dip their bread.

ai2. Passing From Africa To Europe, we come amongst a people who

« ZurückWeiter »