Abstract
CONTENTS
I. Introduction 515
II. Possible conditions for primary syntheses on Earth 515
III. Amino-acids 516
IV. Polypeptides 518
V. Purine and pyrimidine bases. Nucleosides and nucleotides 518
VI. Carbohydrates 520
VII. Aldehydes and organic acids 520
VIII. Amines and amides 520
IX. Imidazole compounds 521
X. Porphyrins 521
XI. General remarks 521