NOTES ON THE REVERSAL OF ASYMMETRY IN THE REGENERATION OF THE CHELÆ IN ALPHEUS HETEROCHELIS

Abstract

We owe to Przibram 1 the interesting discovery that when the larger chela in the genus Alpheus (A. dentipes, A. platyrrhynchus, A. ruber) is removed, the chela undergo a reversal during the ensuing regeneration, a small chela being regenerated from the stump of the large one, while the former small chela, wzhich has not been injured, is directly transformed at the first or second moult into a large one that shows the characteristic structural features of this appendage. A precisely analogous result was obtained in the annelids by Zeleny,2 who found that after amputation of the functional operculum in Hydroides a rudimentary operculum was regenerated in its place, while the rudimentary operculum previously present on the opposite (uninjured) side developed directly into a functional one. These cases are highly interesting since the reversal of asymmetry involves not merely the enlargement of a smaller structure on the uninjured side, but also profound structural and functional changes due to an injury to another part of the body. During the summer of I902 I had an opportunity at Beaufort, N. C.,2 to repeat Przibram's experiments on Alpheus heterochelis, a form in which the differentiation between the two chele is extremely marked, and to make some observations on the control of the regenerative process by the nervous system. The anatomy, habits and development of this form have been carefully described by Brooks and Herrick,3 whose observations give data having an important bearing on the facts to be described.