A　scheme　is　proposed　to　observe　the　collapses　and　revivals　of　a　mesoscopic　superposition　of　coherent　states　in　the　motion　of　a　trapped　ion.　In　the　scheme　the　ion　motion　in　the　x-axis　is　first　prepared　in　a　Schrödinger　cat　state,　and　then　coupled　to　the　motion　in　the　z-axis.　With　the　vibrational　excitation　exchange　between　the　two　modes,　the　mesoscopic　quantum　coherence　collapses　and　revives　periodically,　providing　an　example　for　complementarity.