Note 11 — Chapter I · GENERAL INTRODUCTION

These two kinds of regeneration are post-generation and regeneration proper. The distinction that Roux attempts to make between these two processes is to a certain extent artificial and rests at present on a very unsafe basis, at least in so far as the post-generation of the frog’s embryo is taken as a representative case of this process. Roux states that in the process of regeneration the injured tissues produce each their like in the new part, while in the process of post-generation of the frog’s egg the new cell-material arises in part from the nuclei and yolk-material of the injured half and in part through the accidental position of the nuclear material of the uninjured half. In order more fully to understand this distinction the original description of the process of post-generation given by Roux in his account of the development of half embryos of the frog’s egg must be referred to. In later papers Roux pointed out that the missing half of the frog embryo, as well as of other forms, may be post-generated without any new material appearing at the open side of the embryo. It is unfortunate, I think, that the original term should have been extended to include these other processes that do not partake of the nature of post-generation as at first defined, but are more like the true process of regeneration as described by Roux.