DORMANCY

state of reduced metabolic activity adopted by many organisms under conditions of environmental stress or, often, as in winter, when such stressful conditions are likely to appear. There are few environments in which organisms are not subject to some kind of stress. Some animals migrate vast distances to avoid unfavourable situations; others reduce environmental stresses by modifying their behaviour and the habitats (immediate surroundings) that they occupy. Arctic lemmings, for example, are able to avoid severe winter weather by confining their life in winter to activities beneath the snow cover. Still another mechanism used by some organisms to avoid stressful environmental conditions is that of dormancy, during which an organism conserves the amount of energy available to it and makes few demands on its environment. Most major groups of animals as well as plants have some representatives that can become dormant. Periods of dormancy vary in length and in degree of metabolic reduction, ranging from only slightly lower metabolism during the periodic, short-duration dormancy of deep sleep to more extreme reductions for extended periods of time. a state of reduced metabolic activity adopted by many organisms under conditions of environmental stress or, often, as in winter, when such stressful conditions are likely to appear. See diapause; hibernation. Additional reading Dormancy and related mechanisms are treated in Charles P. Lyman and Albert R. Dawe (eds.), Mammalian Hibernation (1960), examining hibernation and hypothermia in birds and mammals, including articles on such thermally unstable forms as bears; Charles Kayser, The Physiology of Natural Hibernation (1961), an intensive look at hibernation in birds and mammals, including hypothermia and estivation, with emphasis on functional changes; John P. Hannon and Eleanor Viereck, Comparative Physiology of Temperature Regulation (1962), dealing with temperature regulation in both cold- and warm-blooded animals, including hypothermia and hibernation; William V. Mayer, Hibernation (1964), a brief, popular treatment of both birds and mammals; Kenneth C. Fisher (ed.), Mammalian Hibernation (1967), symposium papers dealing directly or indirectly with the topic of mammalian hibernation accompanied by over 1,300 bibliographical references relative to this topic; X.J. Musacchia and Joseph F. Saunders (eds.), Depressed Metabolism (1969), a variety of studies relative to hibernation, hypothermia, and thermic instability; and Harold W. Woolhouse (ed.), Dormancy and Survival (1969), a symposium incorporating a wide variety of review articles covering dormancy in a broad spectrum of organisms, from bacteria through mammals.