THE CIRCULATION 241 



in daily experience. It is a curious fact that the nerves which 

 control the calibre of the bloodvessels tend to overact their 

 part. When an organ demands more blood, it is supplied at 

 the expense of the rest of the body, and especially of the parts 

 most nearly adjacent. This is partly a mechanical effect. If 

 all the houses in a terrace are supplied with water from a 

 common main, the bursting of a water-pipe in one of them 

 will reduce the supply of its neighbours more than it will 

 reduce the supply of houses in distant parts of the town. But 

 vaso-motor nerves, in their compensating adjustment, go 

 farther than this. A thimbleful of blood removed by a leech 

 produces an effect upon an underlying engorged organ alto- 

 gether out of proportion to the hydrostatic requirements of 

 the case. " Cupping " the loins diminishes the congestion of 

 the kidneys. This is the explanation of the curative efficacy 

 of various agents which, with improvements in surgery and the 

 introduction of more reliable drugs, have almost disappeared 

 from the surgeon's armamentarium scarification, blisters, 

 setons, and the like. Such methods have been relegated to 

 veterinary practice. 



There is a marked tendency to see-saw between the skin 

 and the mucous membrane of the alimentary canal. During 

 active digestion, when the " splanchnic area " is full of blood, 

 the skin is cold. Hot fomentations, by dilating the vessels 

 of the skin, diminish congestion of the alimentary tract. An 

 inflamed throat is relieved by a compress round the neck. 

 Conversely, it must be admitted that, in certain persons, slight 

 constriction of the vessels of the skin induces inflammation of the 

 mucous membrane. This is one reason for the almost universal 

 dread of draughts. A draught cools a limited area of the skin. 

 Some of us cultivate a love of draughts. They are the sensible 

 evidence of the entrance of fresh air. Yet we admit reluctantly 

 that certain fragile mortals are not altogether fanciful in sup- 

 posing that a draught may give them a catarrh or a toothache. 

 If asked why they object to draughts, many persons answer 

 that they " are afraid of catching a chill " carrying us back 

 to the time before the clinical thermometer was invented ; to 

 days when the shivering fit, or " rigor," which first calls 

 attention to the fact that the temperature is already two or 

 three degrees above the normal, was supposed to be the com- 



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