This book presents and reviews the results of studies on subjects closely related to the problems of abundance anomalies in globular clusters and covers in particular the problem of deep mixing in globular-cluster red giants and describes a diffusion model and a mechanism for extra mixing in red giants. The author traces the development of scenarios to explain the origin of star-to star variations in elemental abundances in globular clusters: primordial nucleosynthesis and mixing and the background to the proposal of a combined scenario and a model for the chemical evolution of globular clusters. This review provides a useful reference text for graduates and researchers in astrophysics.