ENDOGENOUS DIURNAL PERIODICITY 515 



Table IV. Phaseolus, Leaf Movements; Plants at 



Experimental Temperatures since Germination 



(After Leinweber) 



I will present two examples from my own laboratory (see Tables IV, 

 V). 



We do not yet know how to interpret this temperature independence. 

 I have mentioned some evidence for the induction of compensating 

 processes, but also there are in both plants and animals indications 

 of a different sensitivity to temperature of the several phases within 

 one cycle (Biinning and Tazawa, 1957; Stephens, 1957). But this is 



Table V. Periplaneta americana, Rhythm of Activity 

 (Biinning, 1958a) 



only a differing effect of temperature on the shifting of the phases. 

 Experiments on Periplaneta showed no difference in temperature 

 effects on the speed of the clock when increased temperature was 

 offered during the several phases of its cycles (Figs. 10, 11; Biinning, 

 1958a). 



Though there is no temperature dependence in the length of the 

 periods, some medium temperature is always the optimum condition 



Table VL Phaseolus, Leaf Movements; Percentage of 

 Measurable Periods as Influenced by Temperature; 

 Second Day of Observation (After Leinweber, 1956) 



