The present review is based on the data of the literature, and on the personal experience gained by the author in recent years by studying the histogenesis of spinal ganglia. Probably, the reader will find more than one gap in the biblio- graphy. The author would like to point out that in no case are such gaps due to the voluntary omission of any information, interpretations, or views. The gaps are due only to the difficulties met in trying to master such a vast literature consisting of so many contributions which have appeared over more than a century. An endeavour has been made to report...