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the wide difference in the result must be attributed to a
preference by the worms for one taste over another。
Mental Qualities。There is little to be said on this head。 We
have seen that worms are timid。 It may be doubted whether they
suffer as much pain when injured； as they seem to express by their
contortions。 Judging by their eagerness for certain kinds of food；
they must enjoy the pleasure of eating。 Their sexual passion is
strong enough to overcome for a time their dread of light。 They
perhaps have a trace of social feeling； for they are not disturbed
by crawling over each other's bodies； and they sometimes lie in
contact。 According to Hoffmeister they pass the winter either
singly or rolled up with others into a ball at the bottom of their
burrows。 ｛17｝ Although worms are so remarkably deficient in the
several sense…organs； this does not necessarily preclude
intelligence； as we know from such cases as those of Laura
Bridgman； and we have seen that when their attention is engaged；
they neglect impressions to which they would otherwise have
attended； and attention indicates the presence of a mind of some
kind。 They are also much more easily excited at certain times than
at others。 They perform a few actions instinctively； that is； all
the individuals； including the young； perform such actions in
nearly the same fashion。 This is shown by the manner in which the
species of Perichaeta eject their castings； so as to construct
towers； also by the manner in which the burrows of the common
earth…worm are smoothly lined with fine earth and often with little
stones； and the mouths of their burrows with leaves。 One of their
strongest instincts is the plugging up the mouths of their burrows
with various objects； and very young worms act in this manner。 But
some degree of intelligence appears； as we shall see in the next
chapter； to be exhibited in this work；a result which has
surprised me more than anything else in regard to worms。
Food and Digestion。Worms are omnivorous。 They swallow an
enormous quantity of earth； out of which they extract any
digestible matter which it may contain； but to this subject I must
recur。 They also consume a large number of half…decayed leaves of
all kinds； excepting a few which have an unpleasant taste or are
too tough for them； likewise petioles； peduncles； and decayed
flowers。 But they will also consume fresh leaves； as I have found
by repeated trials。 According to Morren ｛18｝ they will eat
particles of sugar and liquorice； and the worms which I kept drew
many bits of dry starch into their burrows； and a large bit had its
angles well rounded by the fluid poured out of their mouths。 But
as they often drag particles of soft stone； such as of chalk； into
their burrows； I feel some doubt whether the starch was used as
food。 Pieces of raw and roasted meat were fixed several times by
long pins to the surface of the soil in my pots； and night after
night the worms could be seen tugging at them； with the edges of
the pieces engulfed in their mouths； so that much was consumed。
Raw fat seems to be preferred even to raw meat or to any other
substance which was given them； and much was consumed。 They are
cannibals； for the two halves of a dead worm placed in two of the
pots were dragged into the burrows and gnawed； but as far as I
could judge； they prefer fresh to putrid meat； and in so far I
differ from Hoffmeister。
Leon Fredericq states ｛19｝ that the digestive fluid of worms is of
the same nature as the pancreatic secretion of the higher animals；
and this conclusion agrees perfectly with the kinds of food which
worms consume。 Pancreatic juice emulsifies fat； and we have just
seen how greedily worms devour fat； it dissolves fibrin； and worms
eat raw meat； it converts starch into grape…sugar with wonderful
rapidity； and we shall presently show that the digestive fluid of
worms acts on starch。 ｛20｝ But they live chiefly on half…decayed
leaves； and these would be useless to them unless they could digest
the cellulose forming the cell…walls； for it is well known that all
other nutritious substances are almost completely withdrawn from
leaves； shortly before they fall off。 It has； however； now been
ascertained that some forms of cellulose； though very little or not
at all attacked by the gastric secretion of the higher animals； are
acted on by that from the pancreas。 ｛21｝
The half…decayed or fresh leaves which worms intend to devour； are
dragged into the mouths of their burrows to a depth of from one to
three inches； and are then moistened with a secreted fluid。 It has
been assumed that this fluid serves to hasten their decay； but a
large number of leaves were twice pulled out of the burrows of
worms and kept for many weeks in a very moist atmosphere under a
bell…glass in my study； and the parts which had been moistened by
the worms did not decay more quickly in any plain manner than the
other parts。 When fresh leaves were given in the evening to worms
kept in confinement and examined early on the next morning；
therefore not many hours after they had been dragged into the
burrows； the fluid with which they were moistened； when tested with
neutral litmus paper； showed an alkaline reaction。 This was
repeatedly found to be the case with celery； cabbage and turnip
leaves。 Parts of the same leaves which had not been moistened by
the worms； were pounded with a few drops of distilled water； and
the juice thus extracted was not alkaline。 Some leaves； however；
which had been drawn into burrows out of doors； at an unknown
antecedent period； were tried； and though still moist； they rarely
exhibited even a trace of alkaline reaction。
The fluid； with which the leaves are bathed； acts on them whilst
they are fresh or nearly fresh； in a remarkable manner； for it
quickly kills and discolours them。 Thus the ends of a fresh
carrot…leaf； which had been dragged into a burrow； were found after
twelve hours of a dark brown tint。 Leaves of celery； turnip；
maple； elm； lime； thin leaves of ivy； and； occasionally those of
the cabbage were similarly acted on。 The end of a leaf of Triticum
repens； still attached to a growing plant； had been drawn into a
burrow； and this part was dark brown and dead； whilst the rest of
the leaf was fresh and green。 Several leaves of lime and elm
removed from burrows out of doors were found affected in different
degrees。 The first change appears to be that the veins become of a
dull reddish…orange。 The cells with chlorophyll next lose more or
less completely their green colour； and their contents finally
become brown。 The parts thus affected often appeared almost black
by reflected light； but when viewed as a transparent object under
the microscope； minute specks of light were transmitted； and this
was not the case with the unaffected parts of the same leaves。
These effects； however； merely show that the secreted fluid is
highly injurious or poisonous to leaves； for nearly the same
effects were produced in from one to two days on various kinds of
young leaves； n