nerve of the finger, up the arm to the spinal cord, and thence to the brain-cells. These brain- cells send the message to another part of the brain which controls motion, and the cells in this area of the brain send a message down the spinal cord to the nerves supplying the muscles of the arm and finger. These would contract and the linger would be drawn away. This action appears to be instantaneous because nerve impulses pass so rapidly to and from the brain, but it really takes a certain fraction of a moment. Now, supposing for any reason the nerve of the arm and linger was paralysed or cut in two. The brain could not receive a message from the finger, nor could it send a message to the muscles of the linger. No pain or sensation of heat would be felt, and the linger would be burnt. Thus it will be seen that the nerves of the body are a vast telegraphic system carrying messages, or sensations of pain, cold, and heat, to the brain. Every nerve contains what are called sensory fibres, which carry sensation to the brain, and motor fibres, which carry messages from the brain to the muscles. In paralysis there is a break somewhere between the nerves and the brain. A paralysed arm or leg has no power of movement because the brain cannot send its message to the nerves of the muscles of the part. In the same way the 'paralysed limb can feel neither heat, cold, nor pain. The Sympathetic System We have already mentioned the Sympathetic Nervous System. It is that part of the nervous system of the body which has to do with regu- lating the great organs in the chest and abdomen (the lungs, heart, stomach, liver, and intestines), and it also supplies the blood-vessels of the body with nerves. It consists of two chains of nerves. 621 MrOICAL one on either side of the spinal column, and of little masses of ncrvc-ti.ssue called ganglia. These ganglia are, as it were, minute brains, and they send out branches which form net- works of nerves round the organ.s. The function of this system is to regulate the action of the organs of the body associated with nutrition. In invertebrate animals, such as the jellyfish, the worm, etc.. the nervous system has only this form, but the higher animals, or vertebrates (fish, reptiles, amphibians, birds, and mammals),' have a brain, a spinal cord, and nerves in addition. Because we possess a sympathetic system in addition to our higher nervous system our various organs work imperceptibly, without will or con- sciousness, and we are not conscious in health that our stomachs are working, that our hearts are beating, or that our lungs are expanding and contracting. This adds very much to our com- fort and convenience. The sympathetic nervous system is, in a sense, independent of the higher nervous system, but it is really influenced by the brain. Because of this influence, when our organs are out of order, we are made aware of the fact, because we feel pain or discomfort. The thoughtful person will have gathered from this article one fact which bears intensely upon the philosophy of hfe. It is that pain is a good thing. Pain is Nature's warning. It is protective. . If we could not feel pain we should have no knowledge that our hands were burnt, that we were in danger of losing our noses from frost-bite, or that our digestive system was being overtaxed in some way. Mental pain, or unhappiness, can be regarded from the same point of view, but this is a subject which is outside the scope of an article which deals only with simple physiology. The next article in this series will deed with the Skin and its Function, the Muscles, and Fat. COMMON AILMENTS AND THEIR TREATMENT Contimted/rotn pa^e S08, Part 4^ Croup is a spasm of the muscles of the larynx, (which see), and is a disturbance of breathing causing a sudden closure of the glottis — the caused by the diphtheritic membrane over the opening into the windpipe — followed by a long back of the throat. indrawing of the breath, which produces the Cystitis is an inflammation of the bladder, crowing sound. The term "croup " is very which may be either acute or chronic. The loosely applied by non-medical people. For de- condition requires skilled medical and surgical Ecriptive purposes, the late Dr. Savill, in his treatment. Domestic measures may include rest excellent book, " Clinical Medicine," says that and milk diet, and such fluids as milk and soda, there are three types of croup occurring in barley-water, etc. childhood : DandPUfT is an infection of the scalp due to 1. Nervous Croup, in which there is no cough disorganised secretion of the sebaceous glands of or hoarseness. It is due to some irritation of the skin. Sometimes there is too much secretion, nerves supplying the larynx. A child is often and the condition is called moist dandruff or subject to such attacks, if . he is of a rickety moist seborrhoea. The natural oily secretion is type, from improper feeding and unhygienic diminished in dry seborrhoea, and the scalp is conditions. scaly. The scalp is often irritable, and the hair Treatment consists in putting the child into falls out. The condition is apt to be very a hot bath and dashing cold water on the face. chronic if it is not treated. One of the best The provision of rest, quiet, and very careful treatments is to wash the hair once a week diet is the best way to prevent further attacks. with a soap consisting of equal parts of sdft 2. Catarrhal Croup comes on very often at soap and rectified spirits — say one ounce of night, when the child has been suffering from each. This should be mixed into a lather cough and hoarseness for a few hours previously. with soft, warm water, and a little of the It is associated with catarrh of the larynx, and the following pomade should be rubbed into the croup is due to the collection of a thick secretion hair every night : around the larynx and the glottis. Hard paraffin 180 grains The treatment is the same as for nervous Red mercuric oxide 1 20 grains croup, with special attention to the catarrh, Ammoniated mercury 90 grains which may be associated with some fever. Oil of geranium 15 minims 3. Membranous Croup is really diphtheria. Soft paraffin 6 ounces
