Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . PHYSIOLOGICAL EFFECTS, 33 One of the metals is curved over above, so that itmay be brought in contact with the other by a veryshght pressure of the finger. The lower extremitiesof the metals approach, and are made to grasp thethigh of a grasshopper recently killed. On makingcontact between the metals above, the limb will beextended, and on removing the finger, it will againcontract. In this case, as in the frog, the excitingfluid of the galvanic pair
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . PHYSIOLOGICAL EFFECTS, 33 One of the metals is curved over above, so that itmay be brought in contact with the other by a veryshght pressure of the finger. The lower extremitiesof the metals approach, and are made to grasp thethigh of a grasshopper recently killed. On makingcontact between the metals above, the limb will beextended, and on removing the finger, it will againcontract. In this case, as in the frog, the excitingfluid of the galvanic pair is the moisture of the skin,or the natural fluids of the animal, where the skinis removed. 51. The same apparatus, of larger size, servesto show the contractions produced in the leg of afrog. In this case, a great amount of motion is pro-duced by an almost insensible current; and the onlyobjection to the experiment is, the destruction of lifewhich it requires, and the difficulty of always ob-taining the animal. The legs are prepared, as in Mg. Fig. 22, by removing a small portion of the lumbar ver-tebrae, with the extremities attached, from a subject 34 DA viss manual. Fig. 23. recently killed, and stripping off the skin. The legsare shown in the figure in a contracted position,m which they are placed before completing the cir-cuit. The dotted lines exhibit the extended positionwhich they assume under the influence of the current 52. Many animals residing in the water are verysensitive to the galvanic current, owing partly, with-out doubt, to the large surface they ex-pose to the conducting medium, 23 represents a similar galvanic pairto that described above, introduced into aglass vessel containing a leech; one metalbeing on each side of the animal. Oncompleting contact, the leech is instantlydisturbed, and endeavors to escape fromits position in the course of the current. ^j A small fish, in a similar position, alsoexhibits sensibility; and where a strongercur
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
