[Illustration: A lobster, viewed from above.]
Amongst the numerous examples given by Dr. Paley, of the wonderful
manner in which Nature contrives to overcome difficulties, which would
at first appear insurmountable, there is perhaps none more striking than
the mode in which the lobster is released from his case when the
increasing size of his body requires more room. In most animals the skin
grows with their growth. In some animals, instead of a soft skin, there
is a shell, which admits by its form of gradual enlargement. Thus the
shell of the tortoise, which consists of several pieces, is gradually
enlarged at the joinings of those pieces which are called “sutures.”
Shells with two sides, like those of the muscle, grow bigger by addition
at the edge. Spiral shells, as those of the snail, receive this addition
at their mouth. The simplicity of their form admits of this; but the
lobster’s shell being applied to the limbs of his body, as well as to
the body itself, does not admit of either of the modes of enlargement
which is observed in other shells. It is so hard that it cannot expand
or stretch, and it is so complicated in its form that it does not admit
of being enlarged by adding to its edge. How, then, was the growth of
the lobster to be provided for? We have seen that room could not be made
for him in his old shell: was he then to be annually fitted with a new
one? If so, another difficulty arises: how was he to get out of his
present confinement? How was he to open his hard coat, or draw his legs
out of his boots which are become too tight for him? The works of the
Deity are known by expedients, and the provisions of his power extend to
the most desperate cases. The case of the lobster is thus provided for:
At certain seasons his shell grows soft. The animal swells his body; the
seams open, and the claws burst at the joints. When the shell is thus
become loose upon the body, the animal makes a second effort, and by a
trembling motion, a sort of spasm, casts off his case. In this state of
nakedness the poor defenceless fish retires to a hole in the rocks. The
released body makes a sudden growth. In about eight and forty hours a
fresh concretion of humour takes place all over the surface of his body;
it quickly hardens; and thus a new shell is formed, fitted in every part
to the increased size of the body and limbs of the animal. This
wonderful change takes place every year.
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