182 ADVANCED PHYSIOLOGY 



exercised by the vaso-motor system over the small blood 

 vessels of the skin. Persons who live an out-of-door life, 

 although frequently exposed to extremely cold weather, rarely 

 suffer from colds. Those who regularly take cold baths, thereby 

 giving their skin repeated stimulation, are almost immune 

 against colds. 



One is almost certain to take cold if he dresses very 

 warmly, never goes out without heavy wraps, bundles the neck 

 with a fur collar, or turns up the coat collar around the ears 

 when out of doors and, when in doors, lives in very warm 

 rooms. Such a method of caring for one's self will seldom 

 fail to bring on colds. The vaso-motor system of the skin 

 demands exercise just as much as the muscles of the legs or 

 arms. If we fail to use our muscles, they lose the power of 

 acting vigorously. So too, if we fail to give the vaso-motor 

 muscles their exercise, they become sluggish. If we should 

 wear less clothing, the skin would constantly be more or less 

 under the influence of the ever-changing temperature of the 

 air, so that the blood vessels would be kept vigorous and 

 active. We might then frequently feel cold, but we should 

 not " take cold." 



As soon as one finds himself showing a tendency to colds, 

 he should begin at once to invigorate the skin by proper stimuli 

 and thus to tone up the vaso-motor system. A cold bath is 

 the best means of doing this, and if a person when young 

 accustoms himself to bathing every morning in cold water, 

 he will soon find himself almost proof against colds; see page 

 162. Especially is it necessary that the neck should be stimu- 

 lated by cold water, and not wrapped in furs, for this seems 

 to be the part of the body where there is the greatest trouble. 



Colds in themselves are of comparatively little importance, 

 but they sometimes lead to more serious troubles. The in- 

 flammation which starts in the nose, as e.g. in a head cold, 

 may pass into the throat, and then down the trachea into the 

 lungs. A cold in the lungs or the chest is liable to produce 





