Control of Asymmetry 



475 



TABLE I. 



Larval lobsters in the second stage. Original chela symmetrical. 

 Group A Right chela removed 



Group B Left chela removed 



July 24, 1906 



24, 1906 



24, 1 906 



24, 1 906 



24, 1906 



24, 1906 



24, 1906 



24, 1906 



24, 1906 



SIX 



six 

 six 

 six 

 six 

 six 

 six 

 six 

 six 



Oct. 27, 

 Sept. 29, 

 May 31, 

 Oct. 19, 

 Oct. 19, 

 Oct. 19, 

 Oct. 19, 

 July 12, 

 Sept. 22, 



nipper 



nipper 



nipper f 



nipper 



nipper 



nipper 



nipper 



nipper t 



nipper 



* In specimens Nos. 6 and 7, the regenerated right chela was not removed after the moult to the 

 sixth stage on July 14, and on account of unavoidable absence, a record of further moults was not kept. 



■f These specimens, unfortunately, died before there was a clearly developed asymmetry of the chelse. 

 In Nos. 4 and 5, the general appearance of the left claw and the characteristic double tubercle dentition 

 at the base of the jaws indicated that these claws were differentiating into crushers. No. 10 however 

 died on May 31 without having differentiated asymmetrically. 



t It may be of interest to note that No. 15 was much slower in its differentiation than the other speci- 

 mens. At the close of the experiment in 1906, this animal showed no evidence of asymmetry. It was 

 kept through the winter and after three more moults during the following summer, this lobster, in 

 harmony with all the others in Group B, developed a crusher claw on the right chela. 



LOBSTERS IN THE FOURTH STAGE 



At the fourth stage the lobster has made a marked advance 

 toward the adult form. The chelae however are still alike and 

 symmetrical. 



