"Let us take the simplest case,--that which arises daily in the treatment of joint-troubles or broken bones. We put the limb in splints, and thus, for a time, check its power to move. The bone knits, or the joint gets well; but the muscles waste, the skin dries, the nails may for a time cease to grow, nutrition is brought down, as an arithmetician would say, to its lowest terms, and when the bone or joint is well we have a limb which is in a state of disease. As concerns broken bones, the evil may be slight and easy of relief, if the surgeon will but remember that when joints are put at rest too long they soon fall a prey to a form of arthritis, which is the more apt to be severe the older the patient is, and may be easily avoided by frequent motion of the joints, which, to be healthful, exact a certain share of daily movement. If, indeed, with perfect stillness of the fragments we could have the full life of a limb in action, I suspect that the cure of the break might be far more rapid. "What is true of the part is true of the whole. When we put the entire body at rest we create certain evils while doing some share of good, and it is therefore our part to use such means as shall, in every case, lessen and limit the ills we cannot wholly avoid. How to reach these ends I shall by and by state, but for a brief space I should like to dwell on some of the bad results which come of our efforts to reach through rest in bed all the good which it can give us, and to these points I ask the most thoughtful attention, because upon the care with which we meet and provide for them depends the value which we will get out of this most potent means of treatment. "When we put patients in bed and forbid them to rise or to make use of their muscles, we at once lessen appetite, weaken digestion in many cases, constipate the bowels, and enfeeble circulation."[15] When we put the muscles at absolute rest we create certain difficulties, because the normal acts of repeated movement insure a certain rate of nutrition which brings blood to the active parts, and without which the currents flow more largely around than through the muscles. The lessened blood-supply is a result of diminished functional movement, and we need to create a constant demand in the inactive parts. But, besides this, every active muscle is practically a throbbing heart, squeezing its vessels empty while in motion, and relaxing, so as to allow them to fill up anew. Thus, both for itself and in its relations to the areolar spaces and to the rest of the body, its activity is functionally of service. Then, also, the vessels, unaided by changes of posture and by motion, lose tone, and the distant local circuits, for all of these reasons, cease to receive their normal supply, so that defects of nutrition occur, and, with these, defects of temperature.