I.- Section I: Methods for Evaluation of Red Cell Deformability.- Intravascular Rheology of Erythrocytes in Man.- Discussion.- The Aspiration of Red Cell Membrane into Small Holes: New Data.- Red Cell Membrane Deformability: an Examination of Two Apparently Disparate Methods of Measurement.- Discussion of Papers by Brailsford et al. and Bull et al..- Basic Principles of the 'Filterability Test' (FT) and Analysis of Erythrocyte Flow Behavior.- Discussion.- Principles and Techniques for Assessing Erythrocyte Deformability.- Discussion.- Viscometric Techniques and the Rheology of Blood.- Discussion.- Section II: Biochemical Basis for Red Cell Shape and Deformability.- Possible Roles for Membrane Protein Phosphorylation in the Control of Erythrocyte Shape.- Discussion.- Human Red Cell Protein Kinase in Normal Subjects and Patients with Hereditary Spherocytosis, Sickle Cell Disease, and Autoimmune Hemolytic Anemia.- Discussion.- Role of ATP Depletion on Red Cell Shape and Deformability.- Discussion.- The Effects of ATP Depletion on the Response of Erythrocytes to Shear Stress.- Discussion.- Effect of Protein Modification on Erythrocyte Membrane Mechanical Properties.- Commentary.- Section III: Clinical Applications.- Antibody-Induced Spherocytic Anemia. I. Changes in Red Cell Deformability.- Antibody-Induced Spherocytic Anemia. II. Splenic Passage and Sequestration of Red Cells.- Discussion of Papers.- Red Cell Deformability Changes in Hemolytic Anemias Estimated by Diffractometric Methods (Ektacytometry)..- Preliminary Results.- Discussion.- II.- Section I: Sickle Cell Rheology.- Laser Diffraction Patterns of Sickle Cells in Fluid Shear Fields.- Discussion.- Deformability of Normal and Sickle Erythrocytes in a Pressure-flow Filtration System.- Microvascular Blood Flowof Sickled Erythrocytes: A Dynamic Morphologic Study.- Discussion of Papers.- Oxygen Delivery to Muscle Cells during Capillary Occlusion by Sickled Erythrocytes.- Discussion.- Rheology of Sickle Cells and Erythrocyte Content.- Discussion.- Experimentally-Induced Alterations in the Kinetics of Erythrocyte Sickling.- Discussion.- Section II: General Theories of Red Cell Shape, Structure, and Rheology.- The Red Cell Shape as an Indicator of Membrane Structure: Ponder's Rule Reexamined.- Discussion.- Erythrocyte Membrane Elasticity, Fragmentation and Lysis.- Discussion.- Tank Tread Motion of Red Cell Membranes in Viscometric Flow: Behavior of Intracellular and Extracellular Markers (with Film).- Discussion.- Theoretical Aspects and Clinical Applications of the Blood Viscosity Equation Containing a Term for the Internal Viscosity of the Red Cell.- Commentary.- Hemolysis Thresholds in Micro-porous Structures.- Discussion.- Effect of Radio Contrast Media on the Red Blood Cell: An in vitro Study on Human Erythrocytes.- Discussion.- Effects of Storage on the Respiratory Function and Flexibility of Red Blood Cells.- Discussion.- Section III: Summing Up.- Rheological Methods.- The Implications of Rheology for Red Cell Membrane Structure.- Clinical Applications.- Red Cell Rheology: Glossary of Terms.