Genetics is divided into classical Mendelian mechanisms and epigenetic mechanisms. Epigenetic phenomena include, by definition, all phenomena that cannot be accounted for by simple Mendelism. Most of them show cytoplasmic inheritance, but they turn out to be unrelated and operate by different mechanisms. Nowhere are there more numerous and more varied instances of epigenesis than in Paramecium. It is clear that Paramecium is a very useful organism for the study of epigenetic phenomena and may be expected to enlarge and enrich our knowledge of genetics proper in the future. Although crosses between strains with alternative characters provide the basis for both classical Mendelian genetics and epigenetics, numerous additional techniques are used for epigenetic analysis. In this book we will explore all these phenomena.