Аннотация:Morozov's criterion for the stability of a collisionless disk of stars yields lower limits on the mass ratio of the spheroidal component (bulge + halo) and the disk for several galaxies having a measured rotational velocity and disk-population velocity dispersion. In many galaxies the halo mass seems to be comparable with the disk mass, although in late-type galaxies (such as NGC 4062 or the LMC) it may be quite small.