The Muscular and other Formations of the Body.
By Editor
THERE are two hundred and eight bones in the human body, exclusive of the teeth. These bones are composed of animal and earthy materials—the former predominating in youth and the latter in old age—rendering the bones brittle. The most important of the bones is the spine, which is composed of twenty-four small bones, called the vertebræ, one on top of the other, curiously hooked together and fastened by elastic ligaments forming a pillar, so to speak, by which the human frame is supported. The bones are moved by the muscles, of which there are more than five hundred. The red meat of beef, the fat being excluded, is the muscular fabric of the ox. There are two sets of muscles, one to draw the bone one way and another to draw it back again. We cannot better describe the muscles than by comparing them to fine elastic threads bound up in their cases of skin. Many muscles terminate in tendons, which are stout cords such as may be seen traversing the back of the hand, just within the skin, and which can be observed to move when the hand is open or shut. Every motion you make, even the involuntary one of breathing, is preformed through the agency of the muscles. In adults there are about fifteen quarts of blood, each quart weighing about two pounds. This blood is of two kinds, the arterial and veinous. This first is the pure blood as it leaves the heart to nourish the frame, and is of a bright vermilion color. The last is the blood as it returns to the heart, loaded with the impurities of the body, to be there refined, and is of a purple hue. Every pulsation of the heart sends out about two ounces of arterial blood, and so there are from seventy to eighty beats in the minute, a hogshead of blood passes through the heart every hour. In fevers the pulsations are accelerated, the waste of the body goes on faster than it can be recuperated, and consequently death ensues if the fever is not checked. The stomach is the boiler, if we may use such a figure, which drives the human engine. Two sets of muscles, crossing each other transversely, turn the food over and over, churning it up in the gastric juice till it has been reduced to the consistency of thin paste. This process requires from two to four hours. Emerging from the stomach, the food enters the small intestines, where it is mixed with bile and pancreatic juice and converted into chyle. These small intestines are twenty-four feet long, closely packed, of course, and surrounded through their whole length with small tubes which act like suckers, and drawing off the chyle, empty it into a larger tube named the thoracic duct, which runs up the back and discharges its contents into the jugular vein, whence it passes into the heart to assist in forming arterial blood. Only about one-fourth of the human frame, bones included, is solid matter, chiefly carbon and nitrogen, the rest being water. If a man weighing 140 lbs. were squeezed out under a hydraulic press, 105 lbs. of water would run out and thirty-five pounds of dry residue would remain. A man is therefore, chemically speaking, thirty-five pounds of carbon and nitrogen, diffused through five pailfuls of water.—Ed.