An inquiry into the nature of the changes in non-regenerating animals

Abstract

It was shown in a recent publication, 1 that very diverse groups of animals, that ordinarily regenerate such organs as the head, tail, leg, etc., could not be prevented from so doing by destruction of that part of the nervous system supplying the amputated region and adjoining parts. And vice versa, that the lack of regeneration was not due to the absence of stimuli passing through the central nervous system.

The present studies pertain to the adult frog, selected as an example of an animal heretofore not known to replace a missing organ, such as the leg. A large series of sections of the amputated region of the leg, prepared at intervals of several days to over nine months, were studied and compared with similar sections of the leg of the newt, which regenerates its limb quite readily. Perhaps the most striking observation centers about the changes of the bone. In brief the evidence supports the view that that which retards or prevents the growth of the bony tissues correspondingly retards or prevents the growth of the adjoining tissues. It was found that while ordinarily no regeneration occurs, yet each of the tissues could, under appropriate conditions, replace the parts originally removed.