THIRST (AS. J-'urst, Goth. Padrstei, OHG. durst, Ger. Hurst, thirst; connected with Lat. torrere, to parch, Gk. rifwevOat, tersesthai, to become dry, Skt. tars, to thirst). A sensa tion normally due to a lack of wafer in the tis sues of the body. Although the sensation of thirst is referred principally to the mouth and throat, it is not a purely local feeling and can be satisfied by the introduction of fluid into the circulation through various channels. Water may be absorbed and thirst relieved by transfu sion of saline solution into the veins, by injection into the tissues (hypodermoclysis), and to a less extent by absorption front the skin, as well as by drinking. In a state of thirst, the body fluids become reduced in volume, and of higher specific gravity and more saline, and these conditions sufficiently explain the craving for water. Thirst is occasioned physiologically by profuse perspira tion from exercise—especially in a warm. dry
atmosphere—by a highly seasoned diet, or V salty food. Many morbid conditions give rise to thirst ; it is always an accompaniment of fevers and inflammations; diseases which, like cholera asiatica, diabetes, and diarrhoea, are characterized by a great loss of fluid from the body, are productive of thirst. Loss of blood produces a great craving for liquids. As an ex ception to the rule that fevers demand drink, it may be noted that in typhoid fever thirst is sometimes blunted or suppressed. Thirst is most effectively relieved by slightly acidulated drinks, since these provoke an outflow of saliva. In fevers, cracked ice, effervescing drinks, and fruit juices are grateful and help to reduce the temperature.