This paper is concerned with methods of regeneration: morphallaxis, epimorphosis, and regeneration by induction. The last method was demonstrated by investigations to study the restoration of lost regenerative power of the cranial bones in adult dogs and in some other cases. During regeneration by induction an inducing agent, reactive or competent material, and the right conditions for induction must be present. It is emphasized that the method and mechanism of regeneration are one and the same thing. The methods of regeneration specified above differ not only in their formal and secondary features, but also in the essence of their fundamental processes: true reorganization, growth, and induction. Each method of regeneration can be found not only in the pure form, but also in combinations of varying degree and type. Besides regeneration, hypertrophy is also very important for the restoration of parenchymatous internal organs in mammals, but it is not identical with regenerations.