the formation of vegetable mould-第13章
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then they were working carelessly。 I did not at first perceive the
importance of this subject； but merely noticed that the bases of
those triangles which had been drawn in by the apex； were generally
clean and not crumpled。 The subject was afterwards attended to
carefully。 In the first place several triangles which had been
drawn in by the basal angles； or by the base； or a little above the
base； and which were thus much crumpled and dirtied； were left for
some hours in water and were then well shaken while immersed； but
neither the dirt nor the creases were thus removed。 Only slight
creases could be obliterated； even by pulling the wet triangles
several times through my fingers。 Owing to the slime from the
worms' bodies； the dirt was not easily washed off。 We may
therefore conclude that if a triangle； before being dragged in by
the apex； had been dragged into a burrow by its base with even a
slight degree of force； the basal part would long retain its
creases and remain dirty。 The condition of 89 triangles （65 narrow
and 24 broad ones）； which had been drawn in by the apex； was
observed； and the bases of only 7 of them were at all creased；
being at the same time generally dirty。 Of the 82 uncreased
triangles； 14 were dirty at the base； but it does not follow from
this fact that these had first been dragged towards the burrows by
their bases； for the worms sometimes covered large portions of the
triangles with slime； and these when dragged by the apex over the
ground would be dirtied； and during rainy weather； the triangles
were often dirtied over one whole side or over both sides。 If the
worms had dragged the triangles to the mouths of their burrows by
their bases； as often as by their apices； and had then perceived；
without actually trying to draw them into the burrow； that the
broader end was not well adapted for this purposeeven in this
case a large proportion would probably have had their basal ends
dirtied。 We may therefore inferimprobable as is the inference
that worms are able by some means to judge which is the best end by
which to draw triangles of paper into their burrows。
The percentage results of the foregoing observations on the manner
in which worms draw various kinds of objects into the mouths of
their burrows may be abridged as follows：…
Drawn
into the Drawn in； Drawn in；
Nature of Object。 burrows； by or by or
by or near near
near the the the
apex。 middle。 base。
Leaves of various kinds 80 11 9
… of the Lime； basal margin
of blade broad； apex
acuminated 79 17 4
… of a Laburnum； basal part of
blade as narrow as； or some…
times little narrower than
the apical part 63 10 27
… of the Rhododendron； basal
part of blade often narrower
than the apical part 34 。。。 66
… of Pine…trees； consisting of
two needles arising from a
common base 。。。 。。。 100
Petioles of a Clematis；
somewhat pointed at the apex；
and blunt at the base 76 。。。 24
… of the Ash； the thick basal
end often drawn in to serve
as food 48。5 。。。 51。5
… of Robinia； extremely thin；
especially towards the apex；
so as to be ill…fitted for
plugging up the burrows 44 。。。 56
Triangles of paper； of the
two sizes 62 15 23
… of the broad ones alone 59 25 16
… of the narrow ones alone 65 14 21
If we consider these several cases； we can hardly escape from the
conclusion that worms show some degree of intelligence in their
manner of plugging up their burrows。 Each particular object is
seized in too uniform a manner； and from causes which we can
generally understand； for the result to be attributed to mere
chance。 That every object has not been drawn in by its pointed
end； may be accounted for by labour having been saved through some
being inserted by their broader or thicker ends。 No doubt worms
are led by instinct to plug up their burrows； and it might have
been expected that they would have been led by instinct how best to
act in each particular case； independently of intelligence。 We see
how difficult it is to judge whether intelligence comes into play；
for even plants might sometimes be thought to be thus directed； for
instance when displaced leaves re…direct their upper surfaces
towards the light by extremely complicated movements and by the
shortest course。 With animals； actions appearing due to
intelligence may be performed through 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 ｛33｝ that a Sphexan insect
belonging to the same highly…endowed order with antsstocks its
nest with paralysed grass…hoppers； which are invariably dragged
into the burrow by their antennae。 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。 ｛34｝ A cobra…snake was seen by Mr。 Layard ｛35｝ 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
seized the toad by one of its legs and drew it out of the hole。
The instincts of even the higher animals are often followed in a
senseless or purposeless manner： the weaver…bird will
perseveringly wind threads through the bars of its cage； as if
building a nest： a squirrel will pat nuts on a wooden floor； as if
he had just buried them in the ground： a beaver will cut up logs
of wood and drag them about； though there is no water to dam up；
and so in many other
