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[[underline]] Observations [[/underline]], proving, that the [[strikethrough]] sensations [[/strikethrough]] will has a power over sensation universally, to render it more or less acute.
[[underline]] Solution [[/underline]], or answer to the question, necessarily arising from the preceding facts.
[[underline]] Some short scholia [[/underline]].

[[underline]] Problem [[/underline]].
A muscle being given in its natural state, in a living animal body, it is asked how, or by what mechanical means, that muscle contracts, and is again relaxed, at the command of the will?
[[underline]] Observation illustrating the structure and use of the parts concerned. [[/underline]]

[[left margin]] Muscle, how composed. [[/left margin]]
Every muscle of an animal body is observed to be an instrument composed of fibres or lesser muscles, which are joined together every-where, by one common membrane or substance, calld from its appearance, cellular. This substance, when it arrives at the surface of the muscle, becomes uniform, and makes one entire sheath for the whole muscle, or bundle of fibres, and renders it distinct from others.
[[left margin]] Fibres, fleshy ones alone contract. [[/left margin]]
The constituent fibres in many muscles are observed to be partly fleshy, and partly tendinous; the one changing, or being continued, into the other, for the conveniency of insertion and motion. But the observation is universal, that the fleshy fibres alone contract in muscular motion, and that this contraction is always wave-like, or in alternate curls from one extremity to the other of a given fibre.
   We constantly observe, in every muscle, numerous arteries, veins, and nerves. These are generally distributed together, or in the same course, by means of the connecting cellular substance, into every point of the fleshy fibres. Injections, and the knife of the anatomist, have followed them a great way, and reason completes the distribution, since you can nowhere wound the flesh of a muscle, but it shall bleed, and witness a sense of pain.
   Therefore there is a circulation of blood, throughout the whole fleshy substance of a muscle: and further the muscle feels in every part.
[[left margin]] Experiment [[/left margin]]
   In a living animal, if you tie the artery and vein, which principally belong to a given muscle, that muscle is disabled from acting at the command of the will. Steno, a Danish anatomist of the last century, performed this experiment upon the descending aorta, and thereby took away the use of all the lower limbs ( [[underline]] vide Bergerum [[/underline]], p. 296) at once, and restored them at pleasure. Late anatomists have tried it upon lesser vessels, with the same constant success. ( [[underline]] Vide Albini histor. muscul. [[/underline]] p. 19.)
   In a living animal, if you tie the nerve, that supplies a given muscle, that muscle is disabled from acting at the command of the will. This experiment is distinctly mentioned by Galen in his treatise on the muscles, and is approved by the trials of later anatomists. ([[underline]] Alb [[/underline]]. p. 19.)
   From these experiments it is clear, and generally agreed upon, that, in order to the performance of voluntary muscular motion,

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