  At least two significant roles for large scale quantum coherence in living
systems have been suggested: Herbert Fr\"{o}hlich's coherent excitations of
nonlinearly coupled ensembles of large polarizable molecules, with frequencies
in the microwave region, and Fritz Popp's coherent visible photon emission
arising from metabolically active cells. The large difference in frequencies
has made it difficult to see these two phenomena as being linked. Here a case
is made for a potentially large coupling between these modes, and suggestions
are made for the biological roles played by these coherent excitations.
