Control of Asymmetry 



479 



chela the regenerating claw is not always a characteristic crusher 

 from the outset, but frequently displays, at first, characters inter- 

 mediate between those of a crusher and a nipper.^ 



TABLE IV 



Lobsters a year old. Original chela asymmetrical. Group A Crusher chela removed* 



Group B Both chela removed* 



8 specimens 

 6 specimens 



crusher 

 nipper 



nipper 

 crusher 



* After the first moult the regenerated chela were again removed from each lobster. 



ADULT LOBSTERS 



Przibram ('oi, '02) and Morgan ('04) have already observed 

 that in adult lobsters a typical reversal of asymmetry as the result 

 of amputation and regeneration of the chelae has not been found. 

 In the course of my experiments over 200 adults were mutilated 

 by removing one or both chelae. In no case did a crusher develop 

 on the side which had originally carried a nipper, and the same 

 was true, vice versa, for the nipper. As in the yearlings, but not 

 to the same extent, the regenerating crusher chela is not always 

 at first distinguishable as such, but may present characteristics 

 intermediate between the nipper and crusher (Emmel, '06^). 

 Also in certain very rare cases, symmetrical chelae of either the 

 nipper or crusher type may regenerate in place of the amputated 

 asymmetrical limbs (Emmel, 'o6^ '07^) The fact to be empha- 

 sized however is that in these adult lobsters, the amputation of 



1 Compare Emmel '06- and Przibram '07, p. 291. 



