NOTES ON THE REVERSAL OF ASYMMETRY IN 

 THE REGENERATION OF THE CHEL/E IN 

 ALPHEUS HETEROCHELIS. 



EDMUND B. WILSON. 



We owe to Przibram l the interesting discovery that when the 

 larger chela in the genus AlpJicus (A. dcntipes, A. platyrrhynchus t 

 A. rubcr} is removed, the chelae undergo a reversal during the 

 ensuing regeneration, a small chela being regenerated from the 

 stump of the large one, while the former small chela, iv/iic/i lias 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 Hydroidcs a rudimentary operculum was 

 regenerated in its place, while the rudimentary operculum pre- 

 viously present on the opposite (uninjured) side developed di- 

 rectly into a functional one. 



These cases are highly interesting since the reversal of asym- 

 metry 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 1902 I had an opportunity at Beau- 

 fort, N. C., 2 to repeat Przibram's experiments on AlpJicus Jietero- 

 c/iclis, a form in which the differentiation between the two chelae 

 is extremely marked, and to make some observations on the con- 

 trol of the regenerative process by the nervous system. The anat- 

 omy, habits and development of this form have been carefully 

 described by Brooks and Herrick~T whose observations give data 

 having an important bearing on the facts to be described. 



; " Experimentelle Studien liber Regeneration," Arch, fur Eniwkm., XL, 1901. 



2 " A Case of Compensatory Regeneration in the Regeneration of Hydroides dian- 

 thus," Arch, fiir Entwkvi., XIII., 4, 1902. 



3 1 am indebted to the Hon. G. M. Bowers, United States Commissioner of Fish- 

 eries, for the privilege of occupying a table at the Beaufort Laboratory, and to Dr. 

 Caswell Grave, director of the laboratory, for his kind cooperation. 



4 " The Embryology and Metamorphosis of the Macroura," Mem. Nat. Acad. 

 Sci., V., 4 . 



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