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Show vrT TO CT7T T? B wilfred KJU rvOlLLr T. CRENFELL and YOUR BODY THE WIRES OF COMMUNICATION All Communications Are Addressed to Nerve Cellt. CENTRAL .AT.ONCffi OftftERS -rnuSCf.tr. To - PULL. A WAV-HAND-AND. SWAT3 HO SKI TO iScVBco'FlCS.wARN$,cDTAy Here Is a Substation Warning Central That a Mosquito Is Biting Thumb. OME people complain of being 'a bundle of nerves.' Well, every single cell of the body that is alive has to be connected con-nected with a nerve, so really we all are that. Of all the wonders of the body perhaps the nerve-cells are the most marvelous. And yet they are very simple. Some think that nerve-cells nerve-cells are nothing but a lot of electric batteries, though their current travels only about a hundred yards a second, while ordinary electricity travels a hundred and eighty-six thousand miles. Some of these batteries are connected by long wire cells to the substations in various parts of the body, especially to small ones In the chest and belly. These are very sensitive sen-sitive and automatic, and are called sympathetic ganglia, which only means 'nests of cells' forming centers. "Other masses of cells in the brain are called 'special centers,' because they are all for one job like the breathing center, or the center for looking after the pump and pipes, called the vasomotor center. "The wires, of course, conduct the currents ; the central part of the nerve wire is called the axis cylinder. It is made of the best conductor of currents cur-rents known to man. "The nerve currents, of course, go both ways first to the brain. These are called centripetal, that Is, seeking the center. Secondly, they go away from the brain. These are called centrifugal, cen-trifugal, flying from the center. The ; I nerve-Course. j FROM-BRMN. it I JL first are carrying sensations, I. e., 'feelings,' like smell, or sight, or pain, or sound, or taste, and therefore are called, also, sensory nerves. The others oth-ers carry currents that start something some-thing going, like a muscle or a gland, and are called therefore motor nerves, because they say 'get a move on." "You can graft a motor wire or axis to a strange substation, but it will do only what the substation tells it, so we know that it is nothing but a wire. "People used to think that the wires were hollow and carried nerve juices. , They run everywhere from the brain. I Great bulks of main lines run down together. Small bundles come out through holes between every vertebra, like side pipes. This Is a fine way to protect them till 'they get near their Job. Then they bid one another good- ! by, and each goes off to look after his own special work, whatever It may be. "All the nerve-cells are small, but of different sizes. They have an outside coat, which has only recently been discovered. dis-covered. This is full of protoplasm, and In the center of it Is another kind of protoplasm, separated from It by still another cout, said to be only one-ten-mllllonth of a millimeter In thlck-' thlck-' ness. It Is made of tiny fat globules and is a marvelous insulator, more so then the glass of a Leyden jar. This inside is called a nucleus which means the center of importance Just as the first ten cents which you put in your bank is a nucleus, or center; around which the rest will gather. These nuclei watch over the nourishment nourish-ment of the cell and of the whole axis cylinders, and . they alone can make cells grow. "The end nerve-cells are the most raggedy things imaginable. They are so like a tree with endless little branches that they are called 'dendrites,' 'den-drites,' which is only the Greek for tree. , "The nerve-fibers, or neurons, may be yards and yards long. The dendrites are just like the threads of a web. They grow from nerve-cells in between millions of others. "As the main trunk gets farther off from the main station, of course it gets smaller, just like the top branches of a tree. It ends in the tiniest branches it may be in the big toe or the little finger, or heart or liver or eye, or anywhere. any-where. "Here is a nerve-cell and its axis cylinder, or trunk, which is carefully wrapped around as soon as It leaves the skull, in a sheath that protects it and insulates It like the rubber around the copper wire. Remember it is tied up with millions more in bigger bundles bun-dles when it starts. (See picture.) Her you can see it branching out to end in the big toe. Perhaps it is the one that hurt so, when I trod on your toe. "Here is a substation warning central cen-tral that a mosquito is biting a thumb. (See picture.) Central is telling the bl-biceps bl-biceps to pull the thumb away. "We are talking very learnedly about nerve-cells and protoplasm, but really we do not know why a nerve-cell nerve-cell feels, and sees, and tastes, aiji the protoplasm of a muscle-cell only contracts. We do know that anything which makes a chemical change in anything any-thing starts it working, and that that change of substance taking place starts a current instead of starting a simple shortening of the cell, as It does in a muscle-cell. "The ends of the sensory nerves in the brain spread out exactly as do the motor ones in the toe, for instance, and they put their ends so close to motor dendrites, or branches In the brain, that though they do not exactly Join, the current leaps over from one to the other. "Axis cylinders of both kinds of nerves break up into fibrils. They form a network (Latin, plexus) In which each fibril ends in a plate, or in j a cell of some kind. These plexuses are a great safeguard, as, if one fibril is blocked or breaks, the cell can send its messages round by a detour. "The cell can do other things through its nucleus. For instance, it orders all refreshment for the axis cylinder. It can also refuse to do what the sensory nerve asks. "There is another thing to remember remem-ber before we leave 'The Nerves.' It Is this: Nature makes every possible provision for taking care of the delicate deli-cate cells; the finest of fibers, elastic and strong, are woven round and between be-tween them. Along these run tiny pipes, with food and oxygen. Special material also Is stored there for making mak-ing nuclei and refreshing tired-out cells. This meshwork is called 'neuroglia' 'neu-roglia' it is the scaffolding or framework frame-work of the brain or ganglia. But remember re-member this: just as muscle-ceils, nerve-cells may be so badly overworked over-worked that they can never recover. Go on long enough abusing and using a tired nerve-cell and It Just dies. No amount of rest will bring It back again. That Is why we say: 'All work and no play makes Jack a dull liny.' So 'scoot' and play 'instnnter.' " i ( by the Boll Syndicate, lno.) |