. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. PHYSIOLOGY OF THE NERVOUS SYSTEM. 720R the nerve of the leg is to be laid upon the mus- cles of either thigh, and if these muscles be excited to contraction by mechanically stimula- ting the lumbar nerves, or the spinal cord, or by passing a galvanic current through the nerves or the cord, the muscles of the galvanoscopic leg will be simultaneously contracted. If a second and a third galvanoscopic leg be pre- pared, and the nerve of the second be laid on the muscles of the first, and that of the third be 1 lid upon the m
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. PHYSIOLOGY OF THE NERVOUS SYSTEM. 720R the nerve of the leg is to be laid upon the mus- cles of either thigh, and if these muscles be excited to contraction by mechanically stimula- ting the lumbar nerves, or the spinal cord, or by passing a galvanic current through the nerves or the cord, the muscles of the galvanoscopic leg will be simultaneously contracted. If a second and a third galvanoscopic leg be pre- pared, and the nerve of the second be laid on the muscles of the first, and that of the third be 1 lid upon the muscles of the second, contrac- tions will take place in all three whenever the muscles of the prepared thighs are thrown into contraction. Matteucci, to whom we owe the discovery of this important fact (which he terms induced contraction*) has failed to cause a fourth leg to be thus affected. If the galvanoscopic nerve be laid on the muscles of a frog's thigh in which tetanoid con- vulsions have been produced by the cessation of a long continued inverse current, the in- duced contractions will be likewise The annexed woodcuts (Jigs. 3986 &; 398f) will serve to show the manner in which these experiments may be performed. It is plain, then, that during the contraction of muscles, whatever be the means used to sti- mulate them, a force is evolved capable of ex- citing a nerve laid upon the exterior of the con- tracting muscle to such a degree as to cause contraction of the muscles it supplies. What is this force ? The readiness with which it excites the nerve of the galvanoscopic leg re- sembles the action of electricity, and this view of its nature is favoured by the known fact that during muscular contraction heat is evolved, and in some of the marine animals, light also, ac- cording to the observations of Quatrefages. If heat and light be produced during muscular contraction, it is not unreasonable to expect that electricity should be evolved likewise. Matteucci'
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