162 
COMPENSATION. 
great, that one could hardly conjecture beforehand how 
nature would dispose of it. In most animals, the skin 
grows with their 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, consists 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 effort, 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 its 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 coarse 
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 
