TABLE OF CONTENTS Page ACKNOWLEDGMENTS ii LIST OF TABLES v LIST OF FIGURES vii KEY TO ABBREVIATIONS ix ABSTRACT x CHAPTER I INTRODUCTION 1 II LYMPHOCYTE HETEROGENEITY IN THE BLUEGILL 4 Introduction 4 Materials and Methods 8 Results 18 Discussion 52 III LYMPHOCYTE HETEROGENEITY IN THE ALLIGATOR 59 Introduction 59 Materials and Methods 63 Results 69 Discussion 119 IV MEMBRANE IMMUNOGLOBULINS OF BLUEGILL LYMPHOCYTES ... 128 Introduction 128 Materials and Methods 130 iii