Part 42
certain substances are deleterious to some animals and harmless to others, yet one might fancy that, if the coppery principal of an animal's flesh could poison, it is not irrational to think that the same deadly substance would also destroy the animal. The presence of this mineral has never been detected by any chemical test; and, if the poison consisted in copper, how could salting the fish destroy it? In opposition to these objections, it has been maintained that fish may be rendered poisonous by feeding on the marine plants that grow upon these deadly banks. Now, unless it could be proved that copper is not injurious to fish, these same lithophyta and zoophyta would no doubt poison them.
However, it is more than probable that it is to a certain injurious food that these dangerous qualities are to be referred. Various plants that grow in these regions are of a poisonous nature to man, although, as I have just observed, they may not be so destructive to fish. The circumstance of the alimentary tube being more poisonous than any other part seems to warrant the conclusion; and I have observed in the West Indies, that the crabs that feed upon banks where the manchineel is to be found, frequently occasion serious, and sometimes fatal accidents. On the coast of Malabar, crabs are poisonous in the month of October, when the _blue tithymale_ abounds.
Whatever may be the causes of this deadly principle, the effects are most rapid. When a large quantity has been taken, the patient soon dies in strong convulsions; but frequently, when the quantity and the nature of the poison have not been sufficient to occasion death, the body becomes emaciated, the cuticle peels off, particularly on the palms of the hands and the soles of the feet, the hair drops, acute pains shoot through every joint, and the sufferer not unfrequently sinks under a lingering disease. In these cases change of climate has been found the most effectual remedy, and a return to Europe becomes indispensable.
The usual symptoms that denote the presence of the poison, are languor, heaviness, drowsiness, great restlessness, flushing of the face, nausea, griping, a burning sensation, at first experienced in the face and eyes, and then extending over the whole body; the pulse, at first hard and frequent, soon sinks, and becomes slow and feeble. In some cases the salivary glands become tumefied with a profuse salivation; and the body, and its perspiration, are as yellow as in the jaundice. These peculiar symptoms have frequently been known to arise after eating the _rock-fish_.
The remedies that are usually resorted to are stimulants. Capsicum has been considered a powerful antidote; and the use of ardent spirits or cordials has also been strongly urged. It has been observed, that persons who had drunk freely, or who had taken a dram after eating fish that had disordered others, were, comparatively speaking, exempt from the severity of the disease. A decoction of the root of the _sour-sop_, and an infusion of the flowers of the _white cedar_ and the _sensitive plant_ have also been advised by several West India practitioners.
The practice of putting a silver spoon in the water in which fish is boiled, to ascertain its salubrity, is a popular test that cannot be depended on. Fishermen have observed that fish that have no scales are more apt to prove injurious; and those of uncommon size are looked upon as the most dangerous.
To ascertain whether the nature of the fishes' food could thus render them poisonous, Mr. Moreau de Jonnes had recourse to many curious experiments. He took portions of polypes found in the waters reputed dangerous, more
## particularly the _liriozoa Caribaea_, the _millepora polymorpha_, the
_gorgonia pinnata_, the _actinia anemone_, &c., and, having enveloped them in paste, he fed fishes with them; but in no one instance was any prejudicial result observed. He tried in the same manner the _physalis pelagica_ of Lamark, which contains an acrid and caustic fluid; but the fish invariably refused it, nor would they touch fragments of the manchineel apple.
Oysters have been known to produce various accidents; and, when they were of a green colour, it has been supposed that this peculiarity was also due to copper banks. This is an absurdity; the green tinge is as natural to some varieties as to the _esox belone_, whose bones are invariably of the same hue as verdigrise. Muscles frequently occasion feverish symptoms, attended with a red, and sometimes a copper-coloured, efflorescence over the whole body. These accidents appear to arise from some peculiar circumstances. In Boulogne I attended a family in which all the children who had eaten muscles were labouring under this affection, while not another instance of it was observed in the place. In the Bahama Islands I witnessed a fatal case in a young girl who had eaten crabs; she was the only sufferer, although every individual in the family had shared in the meal. The idea of the testaceous mollusca avoiding copper-bottomed vessels, while they are found in abundance on those that are not sheathed, is absurd; this circumstance can be easily explained by the greater facility these creatures find in adhering to wood. There is every reason to believe, that the supposed poisonous oysters found adhering to the copper bottom of a ship in the Virgin Isles, and the occasional accidents amongst the men that ate them, were only so in the observer's imagination, and that part of the ship's company were affected by some other causes. Another report, equally absurd, was that of the fish having gradually quitted the Thames and Medway since coppering ships' bottoms has been introduced! The following may be considered the fish that should be avoided:
The Spanish mackerel, _Scomber caeruleo-argenteus_. The yellow-billed sprat, _Clupea thrissa_. The baracuta, _Esox baracuta_. Grey snapper, _Coracinus fuscus_. The porgie, _Sparus chrysops_. The king-fish, _Scomber maximus_. The hyne, _Coracinus minor_. Bottle-nosed cavallo, _Scomber_. Old wife, _Balistes monoceros_. Conger eel, _Muraena major_. Sword-fish, _Xiphias gladius_. Smooth bottle-fish, _Ostracion globellum_. Rock-fish, _Perca manna_.
I have known accidents arise from the use of the dolphin on the high seas; and, while I was in the West Indies, a melancholy instance of the kind occurred, when the captain, mate, and three seamen of a trading vessel died from the poison; a passenger, his wife, and a boy, were the only survivors, and were fortunately picked up in the unmanageable vessel.
The above catalogue of poisonous fishes is extracted from Dr. Dancer's "Jamaica Practice of Physic," and its correctness fell under my own observation in the Wrest Indies. The different systems and classifications of ichthyologists have produced much confusion, and may lead to fatal errors; I think it therefore advisable to submit to travellers, who may have to visit these unhealthy regions, the names of the _toxicophorous_ fishes according to the French momenclature.
Le poisson arme, _Diodon orbicularis_. La lune, _Tetraodon mola_.--LINN. Le tetraodon ocelle, _T. ocellatus_. Le t. scelerat, _T. scelreatus_. La vieille, _Balistes vetula_. La petite vieille, { _B. monoceros_.--LINN. { _Alutus monoceros_.--CUVIER. Le coffre triangulaire, _Ostracion trigonus_.--BLOCH. La grande orphie, _Esox Brasiliensis_.--LINN. La petite orphie, _E. marginatus_.--LACEPEDE. Le congre, _Muraena conger_.--MINN. Le perroquet, _Sparus psittacus_.--LACEPEDE. Le capitaine, _S. erythrinus_.--BLOCH. La becune, _Sphyraena becuna_. Le thon, _Scomber thynnus_.--LINN. La carangue, _Caranx carangus_.
A work, in which a _synonymous_ catalogue of all the fishes supposed to be poisonous might be found, would be highly desirable, as they generally bear different popular and scientific names, thus producing a dangerous confusion even amongst naturalists; how much more dangerous amongst seafaring people and voyagers!
I cannot conclude this article without noticing the singular properties of those electric fishes denominated the _torpedo-ray_ and the _gymnote_. They had been long known to naturalists, and the ancients attributed their destructive faculties to a magic power that Oppian had recorded in his _Alieuticon_, where he describes a fisherman palsied through the hook, the line, and the rod. This influence being voluntary on the part of the animal, seemed to warrant the belief in its mischievous nature, since it allows itself sometimes to be touched with impunity, while at others it burrows itself under the sand of the beach, when the tide has receded, and maliciously benumbs the astonished passenger who walks over it. This singular fish, which is common in the Mediterranean Sea, has been described both by the Greek and Roman writers; amongst others, by Aristotle and Athenaeus: and Socrates, in his Dialogues, compares a powerful objection, to the influence of the torpedo.
This voluntary faculty has been observed by Lacepede and Cloquet in the Mediterranean, and at La Rochelle. In torpedos kept in water for experimental purposes, Reaumur found that he handled them without experiencing any shock for some time, until they at last appeared to become impatient: he then experienced a stunning sensation along the arm, not easily to be described, but resembling that which is felt when a limb has been struck with a sudden blow. One of the experiments of this naturalist proved the extensive power of this faculty. He placed a torpedo and a duck in a vessel containing sea-water, covered with linen to prevent the duck from escaping, without impeding the bird's respiration. At the expiration of a few minutes the animal was found dead, having been killed by the electric shocks of its enemy.
Redi was the first who demonstrated this faculty. Having laid hold of a torpedo recently caught, he had scarcely touched it, when he felt a creeping sensation shooting up to the shoulder, followed by an unpleasant tremor, with a lancinating pain in the elbow. These sensations he experienced as often as he touched the animal; but this faculty gradually decreased in strength as the animal became exhausted and dying. These experiments he related in a work entitled "_Esperienze intorno a diverse cose naturali_." Florence, 1671.
In 1774, Walsh made some very interesting experiments at the Isle of Re and La Rochelle, and clearly demonstrated this electric faculty in a paper _On the electric property of the torpedo_. In one of them he found that this fish could produce from forty to fifty shocks in the course of ninety minutes. The electrified individuals were isolated; and at each shock the animal gave, it appeared to labour under a sense of contraction, when its eyes sunk deep in their sockets.
The _trichiurus electricus_ of Linnaeus, the _rhinobatus electricus_ of Schneider, and the _gymnonotus electricus_ of _Surinam_, are the species of this singular fish with which experiments have chiefly been made. The _gymnonotus_ is a kind of eel, five or six feet in length, and its electric properties are so powerful that it can throw down men and horses. This animal is rendered more terrific from the velocity of his powers of natation, thus being able to discharge its thunder far and near. When touched with one hand the shock is slight; but when grasped with both, it is so violent that, according to the accounts of Collins Flag, the electric fluid can paralyze the arms of the imprudent experimentalist for several years. This electric action is analogous to that which is obtained by means of the fulminating plate, which is made of glass with metallic plates. Twenty-seven persons holding each other by the hands, and forming a chain, the extremities of which corresponded with the points of the fish's body, experienced a smart shock. These shocks are produced in quick succession, but become gradually weaker as the fluid appears to be exhausted. Humboldt informs us, that, to catch this fish, wild horses are driven into the water, and after having expended the fury and the vigour of the gymnonotus, fishermen step in and catch them either with nets or harpoons. Here we find that the irritable or sensorial power is exhausted through the medium of electricity. These phenomena may be attributed to an electric or Voltaic aura; and the organ of the animal that secretes the fluid resembles in its wonderful structure the Voltaic apparatus. Both the gymnote and the torpedo obey the laws of electricity, and their action is limited to the same conducting and non-conducting mediums. The electric sparks proceeding from the gymnote have been plainly seen in a dark chamber by Walsh, Pringle, Williamson, and others. The fish has four electric organs, two large and two small ones, extending on each side of the body from the abdomen to the end of the tail. These organs are of such a size that they constitute one third of the fish's bulk. Each of them is composed of a series of aponeurotic membranes, longitudinal, parallel, horizontal, and at about one line's distance from each other. Hunter counted thirty-four of these fasciculi in one of the largest. Other membranes or plates traverse these vertically, and nearly at a right angle; thus forming a plexus or net-work of numerous rhomboidal cells. Hunter found no less than two hundred and forty of these vertical plates in the space of eleven inches.
This apparatus, analogous to the Voltaic pile, is brought into action by a system of nerves rising from the spinal marrow, each vertebra giving out a branch; other branches, rising from a large nerve, running from the basis of the cranium to the extremity of the tail. All these ramifications are spread and developed in the cells of the electric organs, to transmit its powerful fluid, and strike with stupor or with death every animal that comes within its reach. Lacepede has justly compared this wonderful mechanism to a battery formed of a multitude of folio-electric pieces.
The electric organ of the _malapterus electricus_ is of a different formation. This fish, found in the Nile and in other rivers of Africa, is called by the Arabs _raash_ or thunder. In this animal the electric fluid extends all round the body, immediately under the integuments, and consists of a tissue of cellular fibres so dense, that it might be compared to a layer of bacon; but, when carefully examined, it consists of a series of fibres forming a complex net-work. These cells, like those in the gymnote, are lubricated with a mucous secretion. The nervous system of this intricate machinery is formed by the two long branches of the pneumo-gastric nerves, which in fishes usually run under each lateral line. Here, however, they approach each other on leaving the cranium, traversing the first vertebra.
Linnaeus had classed the torpedo in the genus _ray_, and hence called it _raia torpedo_. Later naturalists have restored to it its ancient name, as given by Pliny, and termed it _torpedo_, of which four species are described: the _T. narke_, or with five spots; the _T. unimaculata_, marked, as the name indicates, with one spot; the _T. marmorata_, and the _T. Galvanni_.
The ancients placed much faith in the medicinal properties of these fishes. Hippocrates recommends its roasted flesh in dropsies that follow liver affections. Dioscorides prescribed its application in cases of obstinate headaches and rheumatisms. Galen and other physicians recommend the application of the living animal; and Scribonius Largus states that the freedman Anteroes was cured of the gout by this practice. To this day, in Abyssinia, fever patients are tied down on a table, and a torpedo is applied to various parts of the body. This operation, it is affirmed, causes great pain, but is an infallible remedy.
MEMORY AND THE MENTAL FACULTIES.
This noble faculty, the proudest attribute of mankind, justly called the mother of the Muses, is subject to be impaired by various physical and moral causes, while a similar agency can sometimes restore it to its pristine energy, or develope its powers when sluggish and defective. Memory may be considered as the history of the past chronicled in our minds, to be consulted and called upon whenever circumstances stances or the strange complication of human interests demand its powerful aid. Its powers and nature widely differ, and these varieties depend upon education, natural capacities, mode of living, and pursuits. Thus memory has been divided into that faculty that applies to facts, and to that more superficial quality that embraces a recollection of things, to which must be added the memory of localities and words: "Lucullus habuit divinam quamdam memoriam rerum, verborum majorem Hortensius," said Cicero.
It is on this division that Aristotle founded his belief that the brute creation had not the faculty of reminiscence, although he allowed them to possess memory. According to his doctrine, reminiscence is the power of recollecting an object by means of a syllogistic chain of thought; an intellectual link with which animals do not seem to be gifted. Their memory appears solely to consist of the impressions received by the return of circumstances of a similar kind. Thus, a horse that has started on a certain part of a road will be apt to evince the same apprehension when passing the same spot. This is an instinctive fear, but not the result of calculation or the combination of former ideas. Reminiscence is the revival of memory by reflection; in short, the recovery or recollection of lost impressions.
The recollection of things or facts can alone bring forth a sound judgment. It implies a regular co-ordination of ideas, a catenation of reflections, in which circumstances are linked with each other. The chain broken, no conclusion can be drawn. Newton was wont to lose the thread of an important conversation when his mind was in search of an idea. This is the reason why the society of the learned is seldom entertaining to the generality of men. They are considered absent, while their brain is busily employed in pursuits perhaps of great importance; they must therefore be anything but agreeable to those who generally think through the medium of other persons' brains.
The brain is considered to be the seat of memory. When it is injured, remembrance is impaired; and, on the other hand, an accident has been known to improve the recollective faculties. A man remarkable for his bad memory fell from a considerable height upon his head; ever after he could recollect the most trifling circumstance. The effects of different maladies will also produce various results on this faculty. In some instances names of persons and things are completely forgotten or misapplied; at other times, words beginning with a vowel cannot be found. Sudden fright and cold have produced the same effects. An elderly man fell off his horse in crossing a ford in a winter's night; ever afterward he could not bring to his recollection the names of his wife and children, although he did not cease to recognise and love them as fondly as before the accident. Cold has been at all times considered injurious to memory; hence Paulus Aeginus called Oblivion the child of Cold.
In fevers, and a state of great debility, in a disordered condition of the digestive functions, and various affections of the head, we generally find that the attention cannot long be applied to any one subject or a continued train of thoughts; all past circumstances are readily forgotten, while passing occurrences are most acutely observed and felt, excepting in cases of delirium, when we have the perception of surrounding objects or receive an erroneous impression of their nature and agency. In many cases of this nature, we find that conversation produces great excitement and increases the evil, for the subject of such intercourse is generally misconceived and distorted through the medium of a morbid conception, while the past, the present, and the future are grouped in a confused and most heterogeneous and incoherent jumble.
Philosophers have endeavoured to fix the seat of memory in various portions of the brain. The ancients fancied that it was lodged in the posterior part of the cranium; having observed that when persons endeavoured to recollect any thing, they usually scratched the back part of the head. The Arabian physicians entertained a similar belief. Gratarola maintained that a great protuberance of the occiput indicated a good memory. Gall places it above the orbitary cavity of the eye, and even behind it. It has long been thought that persons with protuberant eyes had quick recollections. The physical condition of the brain has also been considered as materially affecting memory. What physiologists have called a moist brain was looked upon as unfavourable to its development; and it was therefore owing to the soft and pulpy condition of the cerebral organs in young children that the difficulty of impressing anything upon their minds arose; the same stupidity being observed in cases where water was supposed to be lodged in the brain. While this humid state was considered as injurious to memory, dryness of the organ was also esteemed an obstacle of a similar nature; and in old age it is by this state of siccity that failure in memory was attempted to be explained. This failure of memory as age advances may, however, be explained in a much more rational manner. Old people will bear in lively recollection the events that attended their childhood, their youth, and manhood; it is only recent occurrences that shed a transient impression on their minds. The cause of this may be considered to arise from the extreme _impressionability_ that prevails in early life, when every organ is prompt in responding to each call upon its powers; when the charms of novelty tinge with a brighter, yet a more lasting lustre, all our pleasurable sensations; when grief had not yet wrung the young heart till its fibres became callous to future pangs, when perfidy and ingratitude have shown us that all is vanity, and calm philosophy has tutored our passions in the school of Adversity. Reason now sits upon the judgment-seat, and all that we then can wonder at that is, at any time we could have wondered at any thing. Why, then, are we to seek for a material theory of the mind, when our daily experience shows us that it is under the influence of so many moral agents?
We have, moreover, convincing proof that the brain may be materially affected, without any deterioration of the mental faculties. Dr. Ferriar mentions a man in whom the whole of the right hemisphere, that is, one half of the brain, was found destroyed, but who retained all his faculties till the very moment of his death. Diemerbrook states another case where half a pound of matter was found in the substance of the brain. O'Hallaran relates the history of a man who had suffered such an injury of the head, that a large portion of his brain was removed on the right side; and extensive suppuration having taken place, an immense quantity of pus, mixed with large masses of the substance of the brain, was discharged at each dressing, through the opening. This went on for seventeen days, and it appears that nearly one half of the brain was thrown out, mixed with the matter, yet the man retained all his intellectual faculties to the very last moment of his dissolution, and through the whole course of the disease, his mind maintained uniform tranquillity. I attended a soldier at Braburne Lees, who had received a wound in the head during ball practice. The ball remained in the brain, and during three weeks large masses of brainular substance were brought away with pus. To the last day of his life he would relate, with every circumstantial particular, the neglect of the comrade by whom he had been wounded, and who fired while he was running to the target to mark the shots. It is somewhat singular, but suppuration of the brain is more offensive than the foulest ulcer, and it is with great difficulty that the pestilential effluvia can be tolerated. These cases plainly show that cerebral diseases have but little influence on the manifestations of the mind.