It has been well established that temperature directly influences the oxygen consumption of poikilotherms and that their activity varies directly with fluctuations in environmental temperatures. The adjustment of metabolic rates to the prevailing temperature is evidenced in several ways by different animals in different seasons and from varying environments.
The oxygen consumption of Emerita talpoida in winter is greater than in summer a t all temperatures below 20ยฐC.' the winter metabolism a t 3ยฐC. being four times as great as the summer rate a t that temperature. This high rate of winter metabolism coincides with the continuation of growth and activity (Edwards and Irving, '43a). Talorchestia megalopthalma, on the other hand, adjusts to winter cold by strict hibernation, and the oxygen consumption in winter is the same as that in summer at a given temperature (Edwards and Irving, '43b). The oxygen consumption of the cunner in winter is a little greater than in summer at the same temperatures (Haugaard and Irving, '43). The metabolism of the Pacific killifish is higher at 15ยฐC. in February and March than a t the same temperature in July and August (Wells, '35). The same effect of season upon metabolism has been shown in the carp (Cronheim, ' 11) and in Mytilus edulis (Bruce, '26). It is thus evident that certain of the poikilotherms can make an internal metabolic adjustment to external conditions.