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158 it would be prudent on his part to stop his machinery. But this would probably be an unwise step, both because he might lose the market, and still more because his machinery would deteriorate by standing idle. The manufacturer therefore prefers to hear the whirr and roar of his machines, although he may feel that they are working at a dead loss to him. He does not expect that the work will improve his machines, but he is sure that it will keep them in good condition.

The muscle-engine, in like manner, deteriorates if it is allowed to stand idle. Sometimes this occurs in disease. In paralysis the limb cannot move, and the inactive muscles waste, become thin and flaccid, and undergo curious molecular changes, converting the muscular matter into fatty-like particles. The wise physician, however, knows this, and, like the manufacturer, he keeps the machinery running. He does this by stimulating the muscles by electricity and causing them to contract. The electricity supplies the stimulus that the nerves cannot give, and the physician keeps up the strength of the muscles and hopes for better times.