164 COMPENS ATION. 



grows with tlieir growth. If. instead of a soft skin, there 

 be a shell, still it admits of a gradual enlargement. If the 

 shell, as in the tortoise, consist of several pieces^ the ac- 

 cession of substance is made at the sutures. Bivalve shells 

 grow bigger by receiving an accretion at their edge ; it is 

 the same with spiral shells at their mouth. The simplici- 

 ty of their form admits of this. But the lobster's shell be- 

 ing applied to the limbs of the body, as well as to the body 

 itself, allows not of either of the modes of growth which 

 are observed to take place in other shells. Its hardness 

 resists expansion ; and its complexity renders it incapable 

 of increasing its size by addition of substance to its edge. 

 How then was the growth of the lobster to be provided for ? 

 Was room to be made for it in the old shell, or was it to 

 be successively fitted with new ones ? If a change of shell 

 became necessary, how was the lobster to extricate himself 

 from his present confinement ? How was he to uncase his 

 buckler, or draw his legs out of his boots? The process, 

 which fishermen have observed to take place, is as follows. 

 At certain seasons, the shell of a lobster grows soft, the 

 animal swells its body, the seams open, and the claws 

 burst at the joints. When the shell has thus become loose 

 upon the body, the animal makes a second eflfort, and by 

 a tremulous spasmodic motion, casts it off. In this state 

 the liberated but defenceless fish, retires into holes in the 

 rock. The released body now suddenly pushes it growth. 

 In about eight-and-forty hours, a fresh concretion of hu- 

 mour upon the surface, i. e. a new shell is formed, adapted 

 in every part to the increased dimensions of the animal. 

 This wonderful mutation is repeated every year. 



If there be imputed defects without compensation, I 

 should suspect that they were defects only in appearance. 

 Thus, the body of the sloth has often been reproached 

 for the slowness of its motions, which has been attributed 

 to an imperfection in the formation of its limbs. But it 

 ought to be observed, that it is this slowness, which alone 

 suspends the voracity of the animal. He fasts during his 

 migration from one tree to another ; and this fast may be 

 necessary for the relief of his over-charged vessels, as well 

 as to allow time for the concoction of the mass of course 

 and hard food which he has taken into his stomach. The 

 tardiness of his pace seems to have reference to the capac- 

 ity of his organs, and to his propensities with respect to 



