522 MATERIA MEDICA AND THERAPEUTICS. 



irrigation with cold water may be used over a part. The cooling 

 that attends evaporation is a powerful means of reducing the 

 local temperature ; and a variety of saline, spirituous, and acid 

 solutions, such as Carbonate or Chloride of Ammonium, Spirit 

 and Water, Brandy and Water, Vinegar and "Water, or various 

 combinations of salts, acids, and spirits, may be employed for 

 this purpose. 



2. The Cutaneous Circulation. This affords us a powerful 

 means of abstracting the body heat, inasmuch as we can 

 modify the fulness of the vessels and the rate of flow through 

 them. Thus we may cool the blood by dilating the cutaneous 

 vessels by the warm bath, by Alcohol, Spirit of Nitrous 

 Ether, or warm draughts, or by these measures combined. 

 Opium and Chloral have the same effect. If the blood- 

 flow be accelerated through the dilated vessels, the refrigeration 

 is increased, and in this way cardiac stimulants of every kind, 

 such as Alcohol and Digitalis, reduce the body temperature. 

 Draughts of water, whether cold or hot, temporarily distend the 

 vessels, and produce a similar effect. The opposite methods 

 for preserving the heat of the body, by contracting the super- 

 ficial vessels and reducing the activity of the cutaneous circula- 

 tion, are of no therapeutical interest. 



3. The Sweat-glands: Diaphoretics, Sudorifics, A.nhidrotics. 

 The function of perspiration is under our control in almost 

 every portion of its complex mechanism. 



a. Measures which increase the amount of perspiration are 

 called diaphoretics or sudorifics. The afferent thermic nerves in 

 the skin can be readily stimulated by means of heat, as 

 described in chapter xv., whether by moist heat in the form of 

 the warm water- or vapour-bath, or various kinds of pack ; by 

 dry heat, as in the Turkish bath ; or by general warmth of the 

 air, of the room, or of the clothing. The familiar effect of 

 Alcohol in inducing perspiration appears to be chiefly produced 

 in the same way. Other afferent nerves may be used to 

 stimulate the sweat-centres reflexly, such as those of the mouth 

 throat, and stomach by hot spiced drinks. Perspiration 

 may be induced by acting on the perspiratory centre directly. 

 This may be accomplished by measures which increase the 

 venosity of the blood, such as narcotics, including Opium, 

 Chloral, Chloroform, Ether, and Alcohol in the later stages of 

 their action ; by Nicotin (Tobacco), by Pilocarpin (Jaborandi) 

 in part ; and by all measures which increase the flow of warm 

 blood through the sweat-centres, such as hot drinks. The 

 efferent nerve-trunks of perspiration may be stimulated by 

 electricity, but this method is not therapeutically employed. 

 The terminations of the nerves in the sweat-glands and the 



