The role of nervous systems in temperature adaptation of poikilotherms.
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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