Annu. Rev. Astron. Astrophys. 1991. 29: 581-625 Copyright © 1991 by Annual Reviews. All rights reserved

Reprinted with kind permission from Annual Reviews, 4139 El Camino Way, Palo Alto, California, USA

Key Words: star formation, Hubble sequence, galaxy evolution, interstellar medium

Table of Contents

• INTRODUCTION
• MOLECULAR MASS DETERMINATIONS
• Theoretical Basis
• Empirical Basis
• RADIAL DISTRIBUTIONS IN SPIRAL GALAXIES
• Unbarred Spiral Galaxies
• Barred Spiral Galaxies
• ¹³CO Observations of Galaxies
• SPIRAL STRUCTURE IN M51
• LOCAL GROUP GALAXIES
• GLOBAL H₂, HI, AND IR IN GALAXIES
• Total H₂ Masses
• Ratio of H₂ to HI
• Gas Mass Fractions in Spiral Galaxies
• The Gas-to-Dust Ratio in Spiral Galaxies
• CO-IR Luminosity Correlation
• STAR FORMATION RATES AND EFFICIENCIES IN GALAXIES
• The Star Formation Efficiency in the Disks of NGC 6946 and M51
• Arm-Interarm Variations
• GALACTIC INTERACTIONS
• Star Formation Efficiencies
• Interaction Morphology
• GALACTIC NUCLEI
• M82
• NGC 1068
• Ultraluminous Infrared Galaxies
• Quasars
• CONCLUSIONS
• REFERENCES