IV 



Page 



Ancient Atmospheres 59 



The Ancient Surfaces 67 



Suggestions for Further Reading 73 



V. THE LABORATORY EXPERIENCE 75 



Introduction 75 



Extraterrestrial Evidence 78 



The Experimental Era 80 



Inorganic Aspects 86 



Polypeptides, Polynucleotides, and the Beginnings 



of Natural Selection 87 



Membranes 98 



Suggestions for Further Reading 1 02 



VI. RECOMMENDATIONS 105 



Introduction 105 



Solar System 106 



The Earth 109 



The Cell 112 



Chemical Evolution 114 



Models for Early Life Forms 118 



The Replication of Surface Patterns - An Alternative 



Entry for Life 120 



Summary 123 



Next Organizational Steps 123 



APPENDIX: MOLECULAR STRUCTURES OF 



IMPORTANT BIOLOGICAL COMPOUNDS 127 



