504 RHYTHMS IN PLANTS AND ANIMALS 



it is driven by external cycles too far removed from its evolved natural 

 period. These external cycles might be close enough to the natural 

 period to insure entrainment and hence synchrony of adjacent cells, 

 but nevertheless sufficiently different from the natural period to im- 

 pair coordination of the constituent intracellular processes that are 

 involved in the B oscillations. 



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