DOUBLE CHELA IN THE FIDDLER CRAB. 155 



experiments on the production of double embryos by constric- 

 tion of Triton eggs by means of hairs and similar experiments of 

 others as mentioned above, certainly indicate the possibility of 

 producing double chelae by similar methods used on the regen- 

 erating buds of Crustacean chelae. Such experiments will be 

 undertaken as soon as suitable material can be obtained. 1 



If the explanation given turns out to be a true one it follows 

 that the mass of embryonic cells which in the ordinary regen- 

 erating bud forms a single chela has because of the partial separ- 

 ation of its material been forced to develop a double one. Or 

 stating the same facts in the convenient terms introduced by 

 Driesch we may say that while the early regenerating bud has 

 ordinarily a prospective value of a single chela the present case 

 certainly shows that the same mass of cells has a prospective 

 potency of tivo chelae. 



INDIANA UNIVERSITY, 

 February 8, 1905. 



1 Andrews, E. A. ("An Aberrant Limb in a Cray-fish," BiOL. BULL., Vol. VI., 

 No. 2, January, '04) attempted to induce the development of monstrosities in the 

 propodites of the chelate. walking legs by making deep cuts in the adult limbs at the 

 places where the new structures were expected to develop. Though 103 operations 

 were made no positive results were obtained. 



