The purposes of this senes were discussed in the preface to Volume I: to present "a range of methods . . . from the physical to the physiological . . . in sufficient detail for the reader to use them in his laboratory" and also to describe "the theoretical backgrounds of the methods and their limita­ tions in membrane biology" so that the reader will be enabled "to evaluate more critically and to understand more fully data obtained by methods foreign to [his] usual experiences. " The chapter by Lee, Birdsall, and Metcalfe with which Volume 2 begins accomplishes these twin goals with a thorough description of the application of nuclear magnetic relaxation measurements to membrane biology together with a lucid and succinct integration of the results of such studies into present concepts of the organi­ zation of membrane lipids. This then permits speculation on the physical basis of membrane permeability. The powerful tool of NMR spectroscopy will have even fuller application with the development of techniques, al­ ready partially exploited, for l3C-Iabeling of specific carbon atoms in lipid molecules and with extension of the observations to membrane proteins. The following two chapters, by Glick and by Laine, Stellner, and Hako­ mori, describe the isolation and characterization of membrane glycoproteins and membrane glycolipids, respectively.