  We discuss the nondissipative Magnus-type force acting on linear defects in
Fermi systems, such as Abrikosov vortices in superconductors, singular and
continuous vortices in superfluid phases of $^3$He, magnetic vortices and
skyrmions in ferromagnets. Spectral flow of fermion zero modes in the vortex
core gives an essential contribution to the nondissipative force, which is
confirmed in Manchester experiments on rotating $^3$He-B. The spectral flow
effect is closely related to the angular momentum paradox.
