ng something as to the extraordinary variety of life and habit to
be found within the range of this single group of arthropods, at first
sight so extremely alike in their shapes, their appearance, their
morals, and their manners. It's perfectly astonishing, though, when one
comes to look into it in detail, how exceedingly diverse spiders are in
their mode of life, their structure, and the variety of uses to which
they put their one extremely distinctive structural organ, the
spinnerets. I will only say here that some spiders use these peculiar
glands to form light webs by whose aid, though wingless, they float
balloon-wise through the air; that others employ them to line the sides
of their underground tunnels, and to make the basis of their
marvellously ingenious earthen trap-doors; that yet others have learnt
how to adapt these same organs to a subaquatic existence, and to fill
cocoons with air, like miniature diving bells; while others, again,
have taught themselves to construct webs thick enough to catch and hold
even creatures so superior to themselves in the scale of being as
humming-birds and sunbirds. This extraordinary variety in the
utilization of a single organ teaches once more the same lesson which
is impressed upon us elsewhere by so many other forms of organic
evolution: whatever enables an animal or plant to gain an advantage
over others in the struggle for life, no matter in what way, is sure to
survive, and to be turned in time to every conceivable use of which its
structure is capable, in the infinite whirligig of ever-varying nature.

MUD.

Even a prejudiced observer will readily admit that the most valuable
mineral on earth is mud. Diamonds and rubies are just nowhere by
comparison. I don't mean weight for weight, of course--mud is 'cheap as
dirt,' to buy in small quantities--but aggregate for aggregate. Quite
literally, and without hocus-pocus of any sort, the money valuation of
the mud in the world must outnumber many thousand times the money
valuation of all the other minerals put together. Only we reckon it
usually not by the ton, but by the acre, though the acre is worth most
where the mud lies deepest. Nay, more, the world's wealth is wholly
based on mud. Corn, not gold, is the true standard of value. Without
mud there would be no human life, no productions of any kind: for food
stuffs of every description are raised on mud; and where no mud exists,
or ca