408 CRUSTACEA. 



(1040.) But the most remarkable part of the phenomenon remains to 

 be noticed: After this extraordinary amputation has been effected, 

 another leg begins to sprout from the stump, which soon grows to be an 

 efficient substitute for the lost extremity, and gradually, though slowly, 

 acquires the pristine form and dimensions of its predecessor. A beau- 

 tiful example of this curious mode of reproducing a lost organ is pre- 

 served in the Museum of Comparative Anatomy in King's College, 

 London, in which the new limb (one of the cheliferous claws) has 

 already attained the form of the old chela, but still remains soft and 

 uncovered by calcareous integument. The process of reproduction is as 

 follows : The broken extremity of the second joint skins over, and pre- 

 sents a smooth vascular membrane, at first flat, but soon becoming 

 conical as the limb begins to grow. As the growth advances, the shape 

 of the new member becomes apparent, and constrictions appear, indi- 

 cating the position of the articulation ; but the whole remains unpro- 

 tected by any hard covering until the next change of shell, after which 

 it appears in a proper case, being, however, still considerably smaller 

 than the corresponding claw on the opposite side of the body, although 

 equally perfect in all its parts. 



(1041.) Mr. H. D. S. Goodsir has shown* that in the Lobster this 

 regenerative faculty does not reside at any part of the claw indifferently, 

 but in a special locality, situated at the basal end of the first joint of 

 each of the legs. This joint is almost filled by a mass of nucleated cells 

 surrounded by a fibrous and vascular band ; and other nucleated cells 

 intervene between this vascular band and the outer crust. The vessels 

 of the band pass onwards for about half an inch, and return upon them- 

 selves, forming loops. When a claw is broken, or otherwise injured or 

 disabled, the Lobster, or Crab, by a violent muscular effort casts it off at 

 the transverse ciliated chink, or groove, which indents the reproductive 

 segment. The new claw is developed by the multiplication of cells, 

 which soon become divided into five groups, answering to the five joints 

 of the future limb ; these nascent joints are folded upon each other in 

 the Crab, but extended in the Lobster ; in both, they are at first en- 

 veloped in a sac formed by the distended cicatrix ; the budding limb 

 ultimately bursts this cicatrix, and its growth is rapidly completed. A 

 great proportion of the reproductive cells contained in the basal ex- 

 tremity of the injured limb is made use of in the production of the new 

 limb ; but a mass of them is retained unchanged at the basal joint, and 

 is ready to renew the reproductive process when needed. In the lower 

 Crustaceans such groups of cells are found at more numerous joints. 



(1042.) The observations made in a former chapter relative to the 

 organs by which the senses of touch, taste, and smell are exercised in 



creature again advances in size, but the new limb more rapidly than the remainder 

 of the animal, until it attains its full relative proportions." Ann. and Mag. Nat. 

 Hist. 1851, vol. vii. p. 300. * Vide Owen on Parthenogenesis, p. 48. 



