Reproduction of Lost Paris in the Lobster. 381 



ecdysis, Ijut that, like the cheUe, they require to undergo 

 three or four ecdyses before the normal size is reached. 

 Chantran has shown that in the crayfish this is not the case, 

 but that the antenniie are there reproduced of full size after 

 the first ecdysis. According to his observations, the antenna3 

 are the only appendages which are reproduced so rapidly. 

 A difference in species may account for this difference in 

 reproduction. The antenn?e of Astacus are relatively much 

 shorter than those of the lobster, and so may be capable of 

 attaining their full size after the first ecdysis. 



Time occupied in the Eepeoduction of Lost Parts. 



Under this heading I propose to discuss briefly the duration 

 of the period which intervenes between the loss of an ap- 

 pendage and its renovation after ecdysis. There appears 

 every reason to suppose that this period may vary with the 

 season of the year in which such renovation takes place, and 

 its duration is also dependent on the precise time at which 

 loss occurs in its relation to a normal period of ecdysis. If 

 an appendage should be lost shortly before a normal ecdysis, 

 it is reasonable to expect that a new rudiment could not be 

 elaborated with sufficient rapidity to be set free at the fol- 

 low^ing ecdysis. Thus the new appendage would only be 

 formed as a rudiment after the first ecdysis, and be set free 

 at the second moult. On the other hand, if several months 

 intervene between the loss of an appendage and the next 

 ecdysis, the rudimentary appendage usually makes its ap- 

 pearance during this interval, and becomes functional after 

 the first ecdysis. 



According to my observations, the antenna, however, do 

 not appear to be reproduced with the same regularity as the 

 chelate and ambulatory limbs. Thus in specimen 0. the 

 right antennal flagellum, which was lost during the winter 

 1882-83, was not reproduced until the third ecdysis, whereas 

 the left was reproduced at the first. Whether this occurrence 

 was normal or due to injury, I am at present unable to say ; 

 but no injury was noted at the time. Spence Bate (9) re- 

 cords a case of reproduction of the flagellum observed by Mr 

 Lloyd in the Hamburg Aquarium, in which the new^ appen- 

 VOL. IX. - - 2 c 



