  We present results of Fabry-Perot and long-slit spectroscopy of the peculiar
galaxy Arp 10. The ionized gas velocity field shows evidence for significant
radial motions in both outer and inner galactic rings. Long-slit spectroscopy
reveals gradients of age and metallicity of stellar population in agreement
with the propagating nature of star formation in the galaxy. We present strong
evidence that a small ``knot'' at 5 arcsec from the center of Arp 10 is its
dwarf elliptic satellite, the most probable ``intruder'' responsible for
triggering the expanding rings in Arp 10.
