The influence of light on the temperature adaptation in Rana temporaria. Adult Rana temporaria L. males were acclimated to 70 and 230 C under long day, short day and continued darkness, Therea~er their oxygen consumption was measured at 230 C under different light conditions (automatic 24-hour registration). The individuals previously kept in darkness exhibited capacity adaptation in the sense of a compensation; long day acclimated frogs showed a respective adaptation, without change of light conditions, only in regard to the night values. For short day acclimated individuals, the test temperature of 230 C is unnaturally high. This fact may have affected our results and led to curves which are extremely difficult to interpret. The results obtained indicate that it is important to control the light conditions not only during the first acclimation period but also during the experiment proper. The experiments provide hints for the assumption that the known temperature independence of the circadian rhythm is based on a fast, almost ideal compensation. Extirpation of the pineal organ reduces oxygen consumption and causes the capacity adaptation to disappear. Oxygen consumption of muscle homogenates of individuals exposed to light during the daytime showed capacity adaptation in the sense of a compensation. E I N L E I T U N GBei vieten wechselwarmen Tieren iiegen sich Anpassungen des Stoffwechsels an ver~inderte Temperaturen feststellen, die als Leistungsadaptationen bezeichnet werden. Sic haben sowohl fiir einen relativ kurzfristigen Ternperaturwechsel w~ihrend einer bestimrnten Jahreszeit, als auch fiir die jahreszeitlichen Anderungen eine Bedeutung. Bei diesen langfristigen Anpassungen kiSnnen neben der Adaptationstemperatur andere Faktoren wichtig sein, wie z. B. die Tagesl~inge. Daher stellte sich das Ziet dieser Arbeit, die Wirkung beider Faktoren auf den Sauerstoffverbrauch erwachsener intakter Grasfr&che (Rana temporaria L.) und yon Muskelgewebehomogenisaten zu untersuchen.Die Jahreszeit kann den Tieren dutch eine innere Jahresuhr angezeigt werden. Dieser endogene Circaannuus-Rhythmus wird -wie der circadiane -dutch Zeitgeber