C. Chemistry 66 D. Medicine 67 Theories of Metachromasy 68 A. Optical Illusion 68 B Impurc Dyes 69 C. Dye Bases 69 D. Tautomers 70 E. pH-Indicators 72 F. Colloidal Theories 72 G. Dimerization and Polymerization 73 H. The Current Status ?4 Physiological Implications of Chromotropes 76 A. Some Properties of Polyacidic Colloids 77 B. Integrity of Connective Tissue 78 C. Blood Clotting 80 D. Cellular Activation and Inhibitiou 81 E. Metaphosphate (Volutin) ..... 82 F. An Evaluation of the Metachromatic Reaction 82 Acknowledgments 84 References 85 Introduction Metachromasy exists when a pure dye...