Page:Popular Science Monthly Volume 18.djvu/822

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cold neglected may, and frequently does, prove itself to be a thing not to be trifled with. Let me, then, pray my readers to remember that small beginnings in not a few instances have big endings, and this especially where disease exists. Let us, then, consider what is a common cold.

In the first place, we must be paradoxical, and affirm that it is not a cold at all. It is rather a heat, if I may so express myself, that is, it is a form of fever, but, of course, of a very mild type when it is uncomplicated by other diseases. It is certainly in the majority of instances due to the effects of cold playing upon some portion of the body, and reacting upon the mucous membrane through the intervention of the nervous apparatus. What is called a cold, then, is in reality a fever; and, though in the majority of instances it is of such a trivial nature as to necessitate few precautions being taken during its attack, yet in some cases it runs a most acute course, and may be followed by great prostration. Even when the premonitory symptoms of a cold are developing themselves, when, for example, what a medical man calls a rigor, or, as it is popularly designated, a shivering is felt, when we would naturally suppose that the animal temperature is below par, it is at that very moment higher than the normal, thus showing the onset of fever.

Before going at once into the symptoms and nature of the disease under discussion, it will be advisable to dip a little into that most interesting department of medical science, physiology, and, indeed, without doing so, it would be quite impossible for the majority of my readers to understand the manner in which cold acts in producing the inflammatory condition of the mucous membrane of the nose, or, as it is called, the Schneiderian membrane, which inflamed condition constitutes a cold in the head. It will be necessary to understand what a mucous membrane is, what its duties are, and how these duties are performed, before entering upon a description of a disease attacking it. To take the mucous membrane of the nose as an example. We find that it is a membrane spread out over a very large area, lining as it does a great many undulations caused by the arrangement of the bones composing the walls of the nostrils, so that a very much greater surface is required to be traversed by the air entering the lungs through the nose—the natural passage—than is required by the actual length of the canal. The object of this is obvious, when we take into account the fact that the temperature of the air is usually either below or above that of the human body, and that it is almost invariably loaded with particles of matter which would irritate the lungs did they find access to them.

The tortuous passage of the nose thus tends in the first place to equalize in some measure the temperature of the atmosphere inhaled with that of the lungs; and, in the second place, the mucus which is secreted by the Schneiderian membrane, being of a tenacious nature.