Fig. 1. Left (or above): Number distribution of current star formation rates (SFR) determined from Halpha luminosities for a sample of irregular (Hunter 1997) and spiral galaxies (Kennicutt 1983). The rates for the Magellanic Clouds are marked (Kennicutt & Hodge 1986). Rates are normalized to the size of the galaxy within a surface brightness of 25 mag/arcsec². The Halpha luminosities were corrected for internal extinction. Right (or below): Normalized star formation rate plotted against integrated galactic M_B

Fig. 2. Concentration of stars formed in a region plotted against the number of stars. The top panel shows stars with M_V < -4 and the bottom panel shows stars with masses 6.5-15 M_sun. The dotted line is that for normal OB associations in the Milky Way and LMC (Massey et al. 1995; value in the lower panel deduced from the IMF). Values for 30 Doradus are deduced from survey by Parker & Garmany (1993). Other references: Constellation III - Dolphin & Hunter (1998); I Zw 18 - Hunter & Thronson (1995); VII Zw 403 - Lynds et al. (1998); NGC 604 - Hunter et al. (1996a); NGC 206 - Hunter et al. (1996b); R 136 - Hunter et al. (1996c)