Annu. Rev. Astron. Astrophys. 1984. 22: 445-70 Copyright © 1984 by Annual Reviews. All rights reserved

2. THE H I CONTENT OF NORMAL GALAXIES

Normalcy is obviously a relative matter. A major stumbling block in the study of the comparative H I contents of galaxies occurs in defining a proper standard of measurement. In this section, we briefly review how the H I content can be determined with a minimum of selection effects in order to optimize the comparison of different samples of galaxies and to determine environmental influences. For more general summaries of the H I properties of galaxies, the reader is referred to other reviews (89, 93, 112).