Translator's Preface.- Author's Preface.- Part I. Review.- Chapter 1 General Properties of the Differential Equations.- Chapter 2 Theory of Integral Invariants.- Chapter 3 Theory of Periodic Solutions.- Part II. Equations of Dynamics and the N-Body Problem.- Chapter 4 Study of the Case with Only Two Degrees of Freedom.- Chapter 5 Study of the Asymptotic Surfaces.- Chapter 6 Various Results.- Chapter 7 Attempts at Generalization.- Erratum. References.-...