  We present HI synthesis observations of the nearby dwarf galaxy IC 2574 (a
member of the M81 group of galaxies) made with the NRAO Very Large Array at
high spatial and velocity resolution (95 pc x 2.6 km/s). The VLA HI
observations show a stunning amount of detail in the form of 48 mostly
expanding HI shells and holes in its neutral interstellar medium. These
features range in size from about 100 (a limit set by the size of the beam) to
about 1000 pc dominating the appearance of the HI surface brightness map. Their
dynamics clearly influence the velocity field of IC 2574. Current star
formation, as traced by H-alpha emission, is predominantly found along the rims
of the larger HI holes, suggesting propagating star formation. On linear scales
of about 95 pc, star formation occurs if the HI surface density reaches values
higher than 10^21 cm^-2. The scaleheight of the HI layer is found to be about
350 pc, considerably thicker than that in massive disk galaxies. This is due to
a lower gravitational potential (for the same observed onedimensional velocity
dispersion of about 7 km/s). A comparison with other galaxies shows that the
energies needed to create the expanding HI structures are the same for all
types of galaxies, at least to first order. The overall statistical properties
of the HI holes and shells in galaxies show clear trends with Hubble type (or
rather mass), such as in their diameter distribution, expansion velocities and
ages.
