inherited habit without any intelligence, although aboriginally thus
acquired. Or the habit may have been acquired through the preservation
and inheritance of beneficial variations of some other habit; and in this
case the new habit will have been acquired independently of intelligence
throughout the whole course of its development. There is no _a priori_
improbability in worms having acquired special instincts through either
of these two latter means. Nevertheless it is incredible that instincts
should have been developed in reference to objects, such as the leaves of
petioles of foreign plants, wholly unknown to the progenitors of the
worms which act in the described manner. Nor are their actions so
unvarying or inevitable as are most true instincts.
As worms are not guided by special instincts in each particular case,
though possessing a general instinct to plug up their burrows, and as
chance is excluded, the next most probable conclusion seems to be that
they try in many different ways to draw in objects, and at last succeed
in some one way. But it is surprising that an animal so low in the scale
as a worm should have the capacity for acting in this manner, as many
higher animals have no such capacity. For instance, ants may be seen
vainly trying to drag an object transversely to their course, which could
be easily drawn longitudinally; though after a time they generally act in
a wiser manner, M. Fabre states {89a} that a Sphex an insect belonging to
the same highly-endowed order with ants stocks its nest with paralysed
grass-hoppers, which are invariably dragged into the burrow by their
antenn . When these were cut off close to the head, the Sphex seized the
palpi; but when these were likewise cut off, the attempt to drag its prey
into the burrow was given up in despair. The Sphex had not intelligence
enough to seize one of the six legs or the ovipositor of the grasshopper,
which, as M. Fabre remarks, would have served equally well. So again, if
the paralysed prey with an egg attached to it be taken out of the cell,
the Sphex after entering and finding the cell empty, nevertheless closes
it up in the usual elaborate manner. Bees will try to escape and go on
buzzing for hours on a window, one half of which has been left open.
Even a pike continued during three months to dash and bruise itself
against the glass sides of an aquarium, in the vain attempt to seize
minnows on the opposite side. {89b} A cobra-snake was seen by Mr. Layard
{90} to act much more wisely than either the pike or the Sphex; it had
swallowed a toad lying within a hole, and could not withdraw its head;
the toad was disgorged, and began to crawl away; it was again swallowed
and again disgorged; and now the snake had learnt by experience, for it
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