492 



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RHYTHMS IN PLANTS AND ANIMALS 



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U"' 



U-" 



LioHT seNstTive 



.'-'" OSCI1.1.ATOR A 



TEMPER ATUUe SENSITIVE 

 eSCILLAIOft. B 



Ir- , I iLr: 



Udn^ 



MUTUAUy 

 tNTRAIHIN& 

 OSCILLATORS 



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LEMeTHeMIKS TRANSIENTS 



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-X PHASE SHIFT 



PHASE SHIFT * 



Fig. 9. The figure illustrates schematically the two-oscillator model 

 described more fuUv in the text. The A and B oscillators are shown "free- 

 running" and "mutually entraining" each other, with a period close to 

 24 hr, at the top of the figure. The black dots represent an arbitrary point 

 in the cycle of the B oscillator, which represents the assayed rhythm in a 

 particular organism. The two lower figures, representing six successive 

 days, illustrate what is to be expected if a signal of light completely and 

 immediately resets the A oscillator and if the B oscillator is gradually re- 

 entrained bv the A oscillator. For simplicity no feedback oi B on A has 

 been shown. 



