Planarian Regeneration deals with regeneration problems including embryogenesis and morphogenesis. The book compares the principles involved in the regeneration processes with those in ontogenesis from the egg. The author also reviews the works of Thomas H. Morgan and Charles M. Child which became the basis for systematic scientific investigation of regeneration. The head regenerates vigorously, with a faster rate behind the eyes, then at various levels along the longitudinal axis of the planarian body. A time-graded regeneration includes inhibitory forces and some genetic codes that determine such rate. The time-graded field has been proven by transplantation experiments; the author addresses the morphological structure to which biochemical factors or processes determine the different rate of regeneration. He notes that the nervous system conforms to these processes as shown by studies of Lender and Klein (1961). The author suggests that the study of regeneration in planarians should involve time considerations quantitatively to explain some substance, if any, from the nervous system that activates the cytoplasm of neoblasts, and then the genome. This book will prove valuable for zoologists and researchers in genetics, biochemistry or molecular biology.