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 vertebrae, 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 vertebrae 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, clavicles or collar-bones, and the scapulae or shoulder-blades, 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 the muscles to assist their motion.
206. SOME OF THE ORGANS OF SENSE IN FISHES are supposed to be 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 the 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 the 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 simple 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 external 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 necessities 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 food; 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 OF 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.
208. THE FECUNDITY OF 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
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of the ocean attach their eggs to sea-weeds. In every instance, however, their fruitfulness far surpasses that of any other race of animals. According to Lewenhoeck, 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 OF 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 the 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.
210. 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 OF HUMAN FOOD.
211. 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