The role of nervous systems in temperature adaptation of poikilotherms.

Integration of the many observations on the role of nervous systems into a logical framework relating to temperature adaptation requires several definitions. Two categories of physiological adaptations are recognized. The first concerns internal state-e.g. body temperature, as a function of environ­ mental temperature. Some animals are strict temperature conformers­ poikilotherms. Other animals are temperature regulators-homeotherms. Still others are conformers in some organs and under some conditions and regulators of temperature of some body regions under specific conditions­ heterotherms. The terms ectothermy and endothermy refer to use of envi­ ronmental and metabolic heat, respectively, in body warming. The prefixes poikiloand homeorefer to int�!ll al state, ectoand endorefer to means of reaching and mai!ltainingbody temperatures. The maintenance of con­ stancy of body lemperature is an example of homeostasis. The second category of physiological adaptation concerns either con­ stancy or variability in activity, in energy production. Many poikilothermic animals compensate for body cooling or heating by changing their metabo­ lism in such a way as to permit relatively constant activity over a wide range of body temperatures. Temperature regulators expend energy in maintain­ ing body temperature over a range of environmental temperatures and thus are capable of relatively constant activity. Metabolic compensation of