TO THE SECOND EDITION When preparing the manuscript for the original
edition of this book we were only partly aware of the pace at which the
field of membrane transport was developing and at which new ideas as
well as new techniques would be applied to it. The fact is that some of
the chapters are now outdated (e. g., the one on the molecular aspects
of transport) and many others require revision in the light of new
information that has appeared in the past five years. However, it is
also true that we overemphasized in the first edition certain points
that now appear less important and underestimated the impact of certain
others that have since assumed a position among the most forcefully
discussed topics of membrane research. In making amends, it was thus
thought useful to include the discussion of these latter problems both
in the theoretical and in the comparative sections and, on the other
hand, to omit some of the less topical subjects. There was a different
reason for rewriting the section on kidney and for dropping the section
on mito- chondria. The help of an expert nephrologist was enlisted for
improving chapter 24, while it was decided that mitochondria represent a
special field both conceptually (being only subcellular particles) and
methodologically (more indirect estimation techniques being involved
than with whole cells or tissues) and that more adequate information can
be found in treatises specializing in work with mitochondria.