hour
one looked in upon them, they were pretty constantly engaged in
devouring some inoffensive fly, or weaving hateful labyrinths of hasty
cord round some fiercely-struggling wasp or some unhappy beetle.

We weren't fortunate enough, I regret to say, to see Eliza's eggs hatch
out from the cocoon; but in other instances, especially in Southern
Europe, I have noticed the little heap of well-covered ova, glued
together into a mass, and attached to a branch or twig by stout silken
cables. If you open the cocoon when the young spiders are just hatched,
they begin to run about in the most lively fashion, and look like a
living and moving congeries of little balls or seedlets. The common
garden spider lays some seven hundred or more such eggs at a sitting,
and out of those seven hundred only two on an average reach maturity
and once more propagate their kind. For if only four lived and throve,
then clearly, in the next generation, there would be twice as many
spiders as in this; and in the generation after that again, four times
as many; and then eight times; and so on _ad infinitum_, until the
whole world was just one living and seething mass of common garden
spiders.

What keeps them down, then, in the end to their average number? What
prevents the development of the whole seven hundred? The simple answer
is, continuous starvation. As usual, nature works with cruel
lavishness. There are just as many spiders at any given minute as there
are insects enough in the world or in their area to feed upon. Every
spider lays hundreds of eggs, so as to make up for the average infant
mortality by starvation, or by the attacks of ichneumon flies, or by
being eaten themselves in the young stage, or by other casualties. And
so with all other species. Each produces as many young on the average
as will allow for the ordinary infant mortality of their kind, and
leave enough over just to replace the parents in the next generation.
And that's one of the reasons why it's no use punishing Lucy and Eliza
for their misdeeds in this world. Kill them off if you will, and before
next week a dozen more like them will dispute with one another the
vacant place you have thus created in the balanced economy of that
microcosm the garden.

Our observations upon Lucy and Eliza, however, had the effect of making
us take an increased interest thenceforth in spiders in general, which
till that time we had treated with scant courtesy, and set us about
learni