8o2 THE POPULAR SCIENCE MONTHLY. 



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 com- 

 mon 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 in- 

 teresting department of medical science, physiology, and, indeed, with- 

 out 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 con- 

 stitutes 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 per- 

 formed, 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 sur- 

 face 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. 



