Digitale Ausgabe
Download
| TEI-XML (Ansicht) | |
| Text (Ansicht) | |
| Text normalisiert (Ansicht) |
Ansicht
| Textgröße | |
| Originalzeilenfall ein/aus | |
| Zeichen original/normiert | |
Zitierempfehlung
Alexander von Humboldt: „Observations respecting the Gymnotes, and other Electric Fish“, in: ders., Sämtliche Schriften digital, herausgegeben von Oliver Lubrich und Thomas Nehrlich, Universität Bern 2021. URL: <https://humboldt.unibe.ch/text/1819-Baron_Humboldts_Personal_Heft1-12-neu> [abgerufen am 23.04.2024].
URL und Versionierung
|
Permalink: https://humboldt.unibe.ch/text/1819-Baron_Humboldts_Personal_Heft1-12-neu |
| Die Versionsgeschichte zu diesem Text finden Sie auf github. |
| Titel | Observations respecting the Gymnotes, and other Electric Fish | ||||
|---|---|---|---|---|---|
| Jahr | 1820 | ||||
| Ort | London | ||||
|
Nachweis in: The London Medical and Physical Journal 43:4:254 (April 1820), S. 299–302.
|
|||||
| Sprache | Englisch | ||||
| Typografischer Befund | Antiqua; Auszeichnung: Kursivierung, Kapitälchen; Fußnoten mit Asterisken und Kreuzen. | ||||
|
Identifikation |
|||||
Statistiken
|
|||||
|299|
The Spaniards confound, under the name of tembladores (trem-blers), all electric fish. They exist in the sea of the Antillas, on thecoasts of Cumana. The Indians of Guayqueries, who are the mostskilful fishers and most industrious people of those regions, brought usa fish which, as they said, benumbed their hands. This fish rises upthe little river of Manzanares. It was a new species of raja, the spotson the sides of which are but slightly visible, and which much resem-bles the torpedo of Galvani. The torpedoes, provided with anelectric organ, which is visible externally from the diaphanous state ofthe skin, form a genus or sub-genus different from the rajas, properlyspeaking.† The torpedo of Cumana was very lively, and extremelyvigorous in his movements, and yet the electric shocks he gave us werebut very weak. They became stronger on galvanising the animal bythe contact of zinc and gold. Other tembladores, real gymnotes, orelectric eels, inhabit the Rio Colorado, the Guarapiche, and manyrivulets which traverse the Chaymas Indies. They enter also thegreat rivers of America,—the Oroonoko, the Amazon, and theMeta; but the force of the current and depth of the water in those
* In his last voyage in America, Baron Humboldt made many original observa-tions respecting the gymnotus and torpedo, which are highly interesting to thephysiologist expressly, as well as to the naturalist in general; and, as the history ofthe Voyage of this philosopher is, from its great price, perhaps not in the pos-session of many of our readers, we shall give some extracts from it, relating tothe animals above designated.—Edit. † Cuvier. Regne Animal, t. ii. p. 156. There are in the Mediterranean, ac-cording to Risso, four species of electric torpedoes, which were formerly con-founded under the name of raja torpedo: namely, torpedo narke, torpedo unimaculata,torpedo galvani, and torpedo marmorata. The torpedo of the Cape of Good Hope,on which Mr. Todd has recently made some experiments, is undoubtedly a non-descript species.|300|parts prevent the Indians from catching them. They see these fishless frequently than they feel electric shocks from them, in swimmingor bathing in the river. It is in the Llanos, especially in the environsof Calabozo, between Morichal and Aniba and Abaxo, that the pondsof stagnant water and the overflowings of the Oronooko (the Rio-Guarico, the Canos of the Rastro, Berito, and Paloma), are filled withgymnotes. We wished at first to make our experiments in the housewe inhabited at Calabozo; but the fear of the electric shocks of thegymnotus is so great, and their effects so much exaggerated by thepeople, that for three days we could not procure any of these animals,although they may be caught with facility, and we had promised theIndians two piastres for each large and vigorous fish they would bringus. This fear of the Indians is the more extraordinary, because theydo not resort to a means for preventing the shocks, in which, they state,they have much confidence. They tell white men, when they areinterrogated respecting the effects of the tembladores, that they maybe touched with impunity, if we chew tobacco. This fable of the in-fluence of tobacco on the electric powers of these animals, is as generalon the continent of South America, as the belief of sailors is in theeffect of garlic and suet on the magnetic needle. Impatient of this long delay, and obtaining only very indeterminateresults from our observations on a living gymnotus very muchweakened, which they had brought us, we went to Cano de Bera, tomake our experiments in the open air on the side of the water. Wesat out on the 19th of March early in the morning, for the littlevillage called Rastro de Abaxo; whence the Indians led us to a smallriver, which, in seasons of great drought, forms a pool of muddywater, surrounded by beautiful trees,* clusia, amyris, and mimoseswith odoriferous flowers. The catching of the gymnotes with a net isvery difficult, because of the extreme agility of these fish. We wouldnot employ the barbasco, that is to say, the roots of the piscidiaerithryna, the jacquinia armillaris, and some species of phyllanthus, which, thrown into a pond, intoxicate or stupify the fish: this mea-sure would have weakened the gymnotes. The Indians told us, theywould fish with horses. † We could not imagine what this extraordi-nary way of fishing could be; but we soon saw our guides return froma savannah, where they had collected several wild horses and mules,which they drove before them into the pool. The noise made by thesplashing of the horses made the fish rise from the bottom of the water,and prepare for the combat. These yellowish and livid eels, similarto large water-snakes, were then seen swimming on the surface of thewater, and pressing themselves against the bellies of the horses andmules. A battle between animals so different presented a very pictu-resque scene. The Indians, armed with harpoons and long sharpcanes, closely surrounded the pool; some of them, too, climbed up
* Amyris lateriflora, A. coriacea, Laurus pichurin, Myroxilon secundum, Mal-pighia reticulata. † Embarbascas con cavallos: properly, make the fish intoxicated or sleepy by meansof horses.|301|the trees whose branches hung over the water, and, by their cries andweapons, prevented the horses from escaping from the water. Theeels defended themselves by repeated discharges of their electric bat-teries. For a long time they seemed likely to become victorious.Many horses sunk under the violence of the shocks they received overall the organs most essential to life; benumbed by the force and fre-quency of them, they disappeared under the water. Others, pantingfor breath, with erect mane, haggard eyes, and signs expressive of ex-treme anguish, rose again, and endeavoured to escape from the stormaround them; but the Indians drove them back again into the middleof the water. Some, however, escaped the vigilance of the fishermen,and gained the shore, stumbling at every pace, and stretching them-selves on the sands, apparently benumbed by the electric shocks of thegymnotes. In less than five minutes, two horses were drowned. Theeel, being five feet in length, pressing itself along the belly of thehorse, makes a discharge from the whole extent of his electric organ,and thus attacks at once the heart, the coeliac plexus, and the wholeof the abdominal nerves. It is obvious that the effect in the horsemust be greater than what it is in a man, when he only touches theanimal by one of his extremities. The horses are, probably, notkilled, but merely benumbed, and are drowned, from their inability toraise themselves during the combat between the rest with the gymnotes.We at first had no doubt but that the battle would end with the deathof all the horses engaged in it; but the impetuosity of it graduallydiminished, and the gymnotes, fatigued, dispersed. They have occa-sion for a long repose and an abundance of nutrition, to repair whatthey have lost of their galvanic power.* They timidly approachedthe margin of the pool, when they were taken by means of little har-poons attached to long cords. When the cords were perfectly dry, theIndians drew them up without receiving any shocks. In a few mi-nutes we had obtained five large gymnotes, most of which were butslightly wounded. Several others were taken towards the evening bythe same means. The temperature of the water in which the gymnotesusually live, is about 26° or 27° Reaumur, (90° or 92° Fahrenheit.)They assured us that their electric power diminished in colder water;and it is very remarkable, as a celebrated naturalist has observed, thatanimals, generally, endowed with organs productive of electric powers,the effects of which are sensible to man, are not found in the air, butin an electro-conductive fluid. The gymnotus is the largest of theelectric fish. I have seen some of them which were from five feet tofive feet three inches in length. The Indians declared that they hadseen still longer. We found that a fish which was three feet teninches long weighed twelve pounds. The transverse diameter of thebody was, without including the anal fin, three inches and five lines,(very nearly four inches English measure.) The gymnotes of Cano de Bera are of a fine olive-green colour.The part below the head is yellow, mingled with red. Two rows of
* The Indians assured us, that, when a troop of horses were driven into thatpool two days in succession, no horse is killed on the second day.|302|small yellow spots are placed symmetrically along the back, from thehead to the point of the tail: each spot surrounds an excretory open-ing; and the skin of the animal is constantly covered with a mucousmatter, which, as Volta proved, conducts electricity twenty or thirtytimes more powerfully than pure water. It is very remarkable, thatno electric fish hitherto discovered is provided with scales. The gymnotus, like the common eel, likes to respire the air on thesurface of the water. The latter is known to creep during the nighton the grassy banks of rivers; but we must not conclude, with M. Bajon, that the fish would die if it were not to come and respire airwithout the water. I have seen a very vigorous gymnotus die onthe dry ground, after having darted out of the adjacent pool. M. Provencal and myself have proved, by our researches on the respira-tion of fishes, that their gills, when wet, are capable of performing thefunctions, both of decomposing atmospheric air, and of abstracting theoxygen dissolved in water. They do not suspend their respiration inthe air, but absorb gaseous oxygen, like a reptile provided with lungs.It is well known that carps are fattened by feeding them out of water,taking care to moisten from time to time their gills with some wetmoss, to prevent them from becoming dry. Fish open their bronchialvalves more in oxygen gas than in water; but their temperature is notraised, and they live as long in vital air as in a mixture of 90 parts ofazote and 16 of oxygen. We have found that tenches, placed underbell-glasses filled with air, absorb in an hour half a cubic centimetre(about one-sixth of a cubic inch English measure) of oxygen. Thisaction takes place in the gills alone; for, fish having cork-collarsadapted to them, and placed thus with their head outwards and therest of the body in a vessel filled with air, do not absorb the oxygenby the rest of the body. It appears, that respiration of air is effectedby the medium of an extremely thin layer of water over the surface ofthe gills. The swimming-bladder of the gymnotus is two feet five inches longin a fish three feet ten inches in length. It is separated from the skinby a mass of fat, and is situate on the electric organs, which fill morethan two-thirds of the animal. The same vessels that are insinuatedbetween the laminæ of these organs, give also numerous branches to theexterior surface of the bladder just mentioned. One hundred parts ofthe fluid contained in this bladder, I found to be constituted of 96parts azote and 4 oxygen. The medullary substance of the brain presents but a slight analogywith the albuminous and gelatinous matter of the electric organs, butthese two substances have this in common,—they receive a large quan-tity of arterial blood, which is deprived of its oxygen in them.*
Observations respecting the Gymnotes, and other Electric Fish. [From Baron Humboldt’s Historical Relation of his Voyage in America. *]
* In his last voyage in America, Baron Humboldt made many original observa-tions respecting the gymnotus and torpedo, which are highly interesting to thephysiologist expressly, as well as to the naturalist in general; and, as the history ofthe Voyage of this philosopher is, from its great price, perhaps not in the pos-session of many of our readers, we shall give some extracts from it, relating tothe animals above designated.—Edit. † Cuvier. Regne Animal, t. ii. p. 156. There are in the Mediterranean, ac-cording to Risso, four species of electric torpedoes, which were formerly con-founded under the name of raja torpedo: namely, torpedo narke, torpedo unimaculata,torpedo galvani, and torpedo marmorata. The torpedo of the Cape of Good Hope,on which Mr. Todd has recently made some experiments, is undoubtedly a non-descript species.|300|parts prevent the Indians from catching them. They see these fishless frequently than they feel electric shocks from them, in swimmingor bathing in the river. It is in the Llanos, especially in the environsof Calabozo, between Morichal and Aniba and Abaxo, that the pondsof stagnant water and the overflowings of the Oronooko (the Rio-Guarico, the Canos of the Rastro, Berito, and Paloma), are filled withgymnotes. We wished at first to make our experiments in the housewe inhabited at Calabozo; but the fear of the electric shocks of thegymnotus is so great, and their effects so much exaggerated by thepeople, that for three days we could not procure any of these animals,although they may be caught with facility, and we had promised theIndians two piastres for each large and vigorous fish they would bringus. This fear of the Indians is the more extraordinary, because theydo not resort to a means for preventing the shocks, in which, they state,they have much confidence. They tell white men, when they areinterrogated respecting the effects of the tembladores, that they maybe touched with impunity, if we chew tobacco. This fable of the in-fluence of tobacco on the electric powers of these animals, is as generalon the continent of South America, as the belief of sailors is in theeffect of garlic and suet on the magnetic needle. Impatient of this long delay, and obtaining only very indeterminateresults from our observations on a living gymnotus very muchweakened, which they had brought us, we went to Cano de Bera, tomake our experiments in the open air on the side of the water. Wesat out on the 19th of March early in the morning, for the littlevillage called Rastro de Abaxo; whence the Indians led us to a smallriver, which, in seasons of great drought, forms a pool of muddywater, surrounded by beautiful trees,* clusia, amyris, and mimoseswith odoriferous flowers. The catching of the gymnotes with a net isvery difficult, because of the extreme agility of these fish. We wouldnot employ the barbasco, that is to say, the roots of the piscidiaerithryna, the jacquinia armillaris, and some species of phyllanthus, which, thrown into a pond, intoxicate or stupify the fish: this mea-sure would have weakened the gymnotes. The Indians told us, theywould fish with horses. † We could not imagine what this extraordi-nary way of fishing could be; but we soon saw our guides return froma savannah, where they had collected several wild horses and mules,which they drove before them into the pool. The noise made by thesplashing of the horses made the fish rise from the bottom of the water,and prepare for the combat. These yellowish and livid eels, similarto large water-snakes, were then seen swimming on the surface of thewater, and pressing themselves against the bellies of the horses andmules. A battle between animals so different presented a very pictu-resque scene. The Indians, armed with harpoons and long sharpcanes, closely surrounded the pool; some of them, too, climbed up
* Amyris lateriflora, A. coriacea, Laurus pichurin, Myroxilon secundum, Mal-pighia reticulata. † Embarbascas con cavallos: properly, make the fish intoxicated or sleepy by meansof horses.|301|the trees whose branches hung over the water, and, by their cries andweapons, prevented the horses from escaping from the water. Theeels defended themselves by repeated discharges of their electric bat-teries. For a long time they seemed likely to become victorious.Many horses sunk under the violence of the shocks they received overall the organs most essential to life; benumbed by the force and fre-quency of them, they disappeared under the water. Others, pantingfor breath, with erect mane, haggard eyes, and signs expressive of ex-treme anguish, rose again, and endeavoured to escape from the stormaround them; but the Indians drove them back again into the middleof the water. Some, however, escaped the vigilance of the fishermen,and gained the shore, stumbling at every pace, and stretching them-selves on the sands, apparently benumbed by the electric shocks of thegymnotes. In less than five minutes, two horses were drowned. Theeel, being five feet in length, pressing itself along the belly of thehorse, makes a discharge from the whole extent of his electric organ,and thus attacks at once the heart, the coeliac plexus, and the wholeof the abdominal nerves. It is obvious that the effect in the horsemust be greater than what it is in a man, when he only touches theanimal by one of his extremities. The horses are, probably, notkilled, but merely benumbed, and are drowned, from their inability toraise themselves during the combat between the rest with the gymnotes.We at first had no doubt but that the battle would end with the deathof all the horses engaged in it; but the impetuosity of it graduallydiminished, and the gymnotes, fatigued, dispersed. They have occa-sion for a long repose and an abundance of nutrition, to repair whatthey have lost of their galvanic power.* They timidly approachedthe margin of the pool, when they were taken by means of little har-poons attached to long cords. When the cords were perfectly dry, theIndians drew them up without receiving any shocks. In a few mi-nutes we had obtained five large gymnotes, most of which were butslightly wounded. Several others were taken towards the evening bythe same means. The temperature of the water in which the gymnotesusually live, is about 26° or 27° Reaumur, (90° or 92° Fahrenheit.)They assured us that their electric power diminished in colder water;and it is very remarkable, as a celebrated naturalist has observed, thatanimals, generally, endowed with organs productive of electric powers,the effects of which are sensible to man, are not found in the air, butin an electro-conductive fluid. The gymnotus is the largest of theelectric fish. I have seen some of them which were from five feet tofive feet three inches in length. The Indians declared that they hadseen still longer. We found that a fish which was three feet teninches long weighed twelve pounds. The transverse diameter of thebody was, without including the anal fin, three inches and five lines,(very nearly four inches English measure.) The gymnotes of Cano de Bera are of a fine olive-green colour.The part below the head is yellow, mingled with red. Two rows of
* The Indians assured us, that, when a troop of horses were driven into thatpool two days in succession, no horse is killed on the second day.|302|small yellow spots are placed symmetrically along the back, from thehead to the point of the tail: each spot surrounds an excretory open-ing; and the skin of the animal is constantly covered with a mucousmatter, which, as Volta proved, conducts electricity twenty or thirtytimes more powerfully than pure water. It is very remarkable, thatno electric fish hitherto discovered is provided with scales. The gymnotus, like the common eel, likes to respire the air on thesurface of the water. The latter is known to creep during the nighton the grassy banks of rivers; but we must not conclude, with M. Bajon, that the fish would die if it were not to come and respire airwithout the water. I have seen a very vigorous gymnotus die onthe dry ground, after having darted out of the adjacent pool. M. Provencal and myself have proved, by our researches on the respira-tion of fishes, that their gills, when wet, are capable of performing thefunctions, both of decomposing atmospheric air, and of abstracting theoxygen dissolved in water. They do not suspend their respiration inthe air, but absorb gaseous oxygen, like a reptile provided with lungs.It is well known that carps are fattened by feeding them out of water,taking care to moisten from time to time their gills with some wetmoss, to prevent them from becoming dry. Fish open their bronchialvalves more in oxygen gas than in water; but their temperature is notraised, and they live as long in vital air as in a mixture of 90 parts ofazote and 16 of oxygen. We have found that tenches, placed underbell-glasses filled with air, absorb in an hour half a cubic centimetre(about one-sixth of a cubic inch English measure) of oxygen. Thisaction takes place in the gills alone; for, fish having cork-collarsadapted to them, and placed thus with their head outwards and therest of the body in a vessel filled with air, do not absorb the oxygenby the rest of the body. It appears, that respiration of air is effectedby the medium of an extremely thin layer of water over the surface ofthe gills. The swimming-bladder of the gymnotus is two feet five inches longin a fish three feet ten inches in length. It is separated from the skinby a mass of fat, and is situate on the electric organs, which fill morethan two-thirds of the animal. The same vessels that are insinuatedbetween the laminæ of these organs, give also numerous branches to theexterior surface of the bladder just mentioned. One hundred parts ofthe fluid contained in this bladder, I found to be constituted of 96parts azote and 4 oxygen. The medullary substance of the brain presents but a slight analogywith the albuminous and gelatinous matter of the electric organs, butthese two substances have this in common,—they receive a large quan-tity of arterial blood, which is deprived of its oxygen in them.*
* We stop, at present, at the conclusion of these preliminary observations,because we wish to give an account of Baron Humboldt’s experiments on theelectric powers of the gymnotes in an uninterrupted manner, and the limits of theJournal will not permit us to do this in the present Number.—Edit.