PHYSICAL PROPICRTIES OF THE GYMXOTI. 



course, ill rcfurence to its curious pliybieal properties. 

 When toiiclied with the hand or an electric conductor, 

 it communicates a pungent sensation, similar to an 

 electrical shock. The organs which produce this 

 effect consist of four groups of parallel membranaceous 

 lamina;, situated very near each other and almost hori- 

 zontally extending from the skin to the central medial 

 plane of the body, and connected by nimierous trans- 

 verse vertical lamina?. The prismatic canals or cellules 

 intercepted by these lamin;* are charged with a pecu- 

 liar gelatinous substance, while an abundance of nerves 

 permeates the whole apparatus ; which is said, when 

 fully vigorous, to be able to knock down a man, and 

 benumb the stricken limb for several hours. It has 

 been conjectured that it is by this means the eel ob- 

 tains its prey, stupifying the smaller fishes, and other 

 animals, which come within its reach. 



Though externally allied to the eel, says an able 

 writer, yet if that part of the body was cut off which 

 contains the nutrient, the respiratory, and generative 

 organs — all the parts, in fact, which are essential to 

 the existence of tlie Gymnotus as a mere fish — it would 

 present a very different appearance to the slender eel 

 in its short and thick-bodied form. Its long electric 

 organs are, so to speak, an extraneous appendage to the 

 true fish, and its eel-like form is therefore accidental. 

 The back -bone and muscles are of necessity coextended 

 with the electric organs for their support and motion; 

 and the air-bladder stretches along the produced electro- 

 (diorous trunk to secure a suitable specific levity. Two 

 dorsal nerves are prolonged from the fifth and eighth 

 cerebral nerves, for ordinary sensation and motion. The 

 Bpinal cord is produced along the vertebral column, for 

 the exclusive supply of the electrical organs. The 

 electricity winch they discharge decomposes chemical 

 compounds, produces the spark, and magnetizes iron, 

 as does that of the Torpedo. But the magnetiz- 

 ing power seems to be relatively weaker, while the 

 benumbing shock communicated to other animals is 

 stronger than in any other electric fish. 



It gives this shock with the greatest force when 

 touched under the belly, or in the pectoral fin, and 

 always acts without the least muscular exertion in the 

 fins, head, or body. It acts, too, of its own will, and 

 the discharge is more or less powerful according to the 

 animal's pleasure. 



Those electrical properties were fiist discovered by 

 Van Berkal. As far as the American fish was con- 

 cerned, little was known of them by the scientific 

 world until described by the astronomer Richer, who 

 visited Cayenne in 1671. "I was much astotdshed," 

 he writes, " to see a fish some three or four feet in 

 'ength, and resembling an eel, deprive of all motion 

 for a quarter of an hour the arm and neighbouring 

 parts which tciuched it. I was not only an ocular 

 witness of the effect produced by its touch, but I have 

 myself felt it, on touching one of these fishes while still 

 living, though wounded by the hook the Indians had 

 employed in drawing it from the water." 



For the first precise and philosophical account of it 

 we are indebted to Humboldt, who drew it up from 

 Bunpland's observations. 



In crossing the wide grassy llanos of the province of 



Caracas, in order to embark at San Fernando del A pure 

 on his voyaye up the Orinoco, M Bunpland stopped 

 at Calabozo. His object was to investigate with care 

 and completeness the history of the Gymnotus, which 

 is abundant in the neighbourliood ; and some Indians 

 conducted him to the Cano de Bera, a muddy and 

 stagnant lake, surrounded by luxuriant vegetation, 

 among which the Clusia rosea, the Ilyraena'a courba- 

 ril, the Indian fig, and some fragrant floweiing mimosas 

 shone pre-eminent. The Indians then collected a troop 

 of half-wild horses, and surrounding the marsh, as 

 hunters surround the forest where some wild animal 

 lies concealed, drove them into the miry waters, shout- 

 ing and screaming vociferously. The horses rushed 

 into the water, when the eels, stunned and alarmed 

 by the noise, the tumult, and the agitation, defended 

 themselves by repeated discharges of their batteries, 

 which seriously wounded their involuntary enemies. 



" I wish, says Humboldt," that a clever artist could 

 have depicted the most animated period of the attack," 

 which hag been done, as the reader will see, on 

 turning to the Illustiation. "The groups of Indians 

 surrounding the pond ; the horses with their manes 

 erect and eyeballs wild with pain and fright, striving to 

 escape from the electiic storm which they had roused, 

 and driven back by the shouts and long whips of the 

 excited Indians; the livid yellow eels, like great water- 

 snakes, swimming near the surfiice and pursuing their 

 enemy— all these objects presented a picturesque and 

 exciting ensemble. 



" In less than five minutes two horses were killed. 

 The eel, being more than five feet in length, glides bo 

 neath the body of the horse, and discharges the whole 

 extent of its electric organ, attacking simultaneously 

 the heart, the digestive viscera, and, above all, the 

 gastric plexus of nerves. I thought the scene would 

 have a tragic termination, and expected to see most 

 of the quadrupeds killed ; but the Indians assured me 

 the fishing would soon be finished, and that only the 

 first attack of the Gymnotus was really formidable." 



After the combat had endured for about fifteen 

 miimtes, the alarm of the mules and horses gradually 

 decreased ; they no longer erected their manes, and 

 their eyes expressed less pain and terror. They were 

 no longer struck down in the water, as if seized by an 

 invisible hand; and the eels, instead of swimming to 

 the attack, retreated from their assailants, and made 

 for the marshy bank. 



The Indians then easily captured them with har- 

 poons attached to long coids, and they were landed 

 without having any oi)portunity of communicating a 

 shock. 



THE EIPPOCAMPtrS 



The Ifippocampus is a gonus of highly curious 

 aspect, known in English nautical parlance as the 

 Sea-horse Pipe-pot. The best-known species is the 

 Synr/naihus hippucmiqnts of LinnKus, or the Hippo- 

 campus* hrevirostris of Cuvier. Its average length is 

 * From 'iVto;, horse, and xtc/trct, fish. 



