  We present a selected few cases in which the sense of chirality of filament
barbs changed within as short as hours. We investigate in detail a quiescent
filament on 2003 September 10 and 11. Of its four barbs displaying such changes
only one overlay a small polarity inversion line inside the EUV filament
channel (EFC). No magnetic elements with magnitude above the noise level were
detected at the endpoints of all barbs. In particular, a pair of barbs first
approached toward and then departed from each other in H-alpha, with the barb
endpoints migrating as far as ~10". We conclude that the evolution of the barbs
was driven by flux emergence and cancellation of small bipolar units at the EFC
border.
