47^ Victor E. Emjnel 



A point which should receive further investigation for this 

 stage is the time of mutilation with reference to the moult. It 

 will be observed that in the above experiments the mutilations 

 were made several days after moulting. In another experiment 

 the left chela was removed from a number of lobsters on the day 

 in which they had moulted to the fifth stage. Only four of the 

 specimens lived until the chelae displayed asymmetrical characters, 

 but it is interesting to note that for each lobster, a crusher devel- 

 oped on the right or uninjured chela, and that the regenerated 

 claw was a nipper. This result indicates that possibly the asym- 

 metry may be controlled at this stage, provided that the mutila- 

 tions are made sufficiently early. 



IMMATURE LOBSTERS, A YEAR OLD 



With the assistance of Mr. E. W. Barnes, superintendent of 

 the Experiment Station of the Rhode Island Fish Commission, 

 we succeeded in keeping about thirty-five lobsters, hatched in 

 July, 1905, until the following summer. At this time these year- 

 ling lobsters were all in about the twelfth stage and averaged two 

 inches in length. The asymmetry of the chelae is clearly developed 

 at this age. But when it is recalled that the lobster does not attain 

 sexual maturity until about the fifth year, it will be readily appre- 

 ciated that these yearling lobsters were still quite immature and 

 at a period of rapid growth. It seemed desirable therefore to 

 ascertain the degree of stability which the asymmetry may have 

 attained at this age as compared with the adult. The experimental 

 results obtained are shown in Table IV. 



In this experiment on yearling lobsters, 15 were mutilated by 

 the autotomous removal of the crusher chelae (Group A), and 14 

 were mutilated by the removal of both chelae (Group B). In 

 both groups the regenerated claws were again amputated. In no 

 case in either group did these mutilations and consequent regen- 

 erations reverse the original asymmetry. Each yearling lobster 

 retained its original right or left handed arrangement of the 

 chelae. 



It should be added however that in the case of the crusher 



