  The evolution of stripe patterns in type-I superconductors subject to a
rotating in-plane magnetic field is investigated magneto-optically. The
experimental results reveal a very rich and interesting behavior of the
patterns. For small rotation angles, a small parallel displacement of the main
part of the stripes and a co-rotation of their very ends is observed. For
larger angles, small sideward protrusions develop, which then generate a zigzag
instability, ultimately leading to a breaking of stripes into smaller segments.
The short segments then start to co-rotate with the applied field although they
lag behind by approximately $10^\circ$. Very interestingly, if the rotation is
continued, also reconnection of segments into longer stripes takes place. These
observations demonstrate the importance of pinning in type-I superconductors.
