Zur Analyse des Zeitsinnes bei Periplaneta americana

The running activity was used as a measure of the course of the endogenous diurnal periodicity in Periplaneta americana. The influence of low temperatures (+5°, +3°, -2°), which acted on the diurnal cycle at different times was tested. In one of the two half cycles the delay of the internal clock due to the chilling was smaller or equal to the duration of the chilling. During this phase, at least at temperatures greater than zero, a minimum time of chilling was necessary in order to demonstrate the delay clearly. In the other half cycle the delay is greater than the duration of the chilling. It is concluded that oscillations of relaxation are the basis of these phenomena. The phase of tension requires a minimum temperature. Below this minimum a gradual relaxation occurs. The phase of relaxation continues at low temperatures, but after some time it is gradually delayed. The normal 24-hour light-dark cycle regulates these oscillations in such a way that the phase of tension begins in the second half of the light phase and it attains its maximum in the first part of the dark phase.