Devout writers speak of a wise provision of Nature. "If," say they, "the
speed of a mouse were as much less than that of a horse as its body is
smaller, it would take two steps per second, and be caught at once."
Would not Nature have done better for the mouse had she suppressed the
cat? Is it not a fact that small animals often owe their escape to their
want of swiftness, which enables them to change their direction readily?
A man can easily overtake a mouse in a straight run, but the ready
change of direction baffles him.
M. Plateau has experimented on the strength of insects, and the facts
are unassailable. He has harnessed carabi, necrophori, June-beetles
(Melolontha), and other insects in such a way that, with a delicate
balance, he can measure their powers of draught. He announces the result
that the smallest insects are the strongest proportioned to their size,
but that all are enormously strong when compared bulk, for bulk, with
vertebrates. A horse can scarcely lift two-thirds of its own weight,
while one small species of June-beetle can lift sixty-six times its
weight; forty thousand such June-beetles could lift as much as a
draught-horse.
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