The Formation of Vegetable Mould Through the Action of Worms: With Observations on Their HabitsDarwin, Charles
Science
The Formation of Vegetable Mould Through the Action of Worms: With Observations on Their Habits
Darwin, Charles
Earthworms; Humification; Soils
_Petioles_.—We will now turn to the petioles or foot-stalks of compound
leaves, after the leaflets have fallen off. Those from _Clematis
montana_, which grew over a verandah, were dragged early in January in
large numbers into the burrows on an adjoining gravel-walk, lawn, and
flower-bed. These petioles vary from 2½ to 4½ inches in length, are
rigid and of nearly uniform thickness, except close to the base where
they thicken rather abruptly, being here about twice as thick as in any
other part. The apex is somewhat pointed, but soon withers and is then
easily broken off. Of these petioles, 314 were pulled out of burrows in
the above specified sites; and it was found that 76 per cent. had been
drawn in by their tips, and 24 per cent by their bases; so that those
drawn in by the tip were a little more than thrice as many as those drawn
in by the base. Some of those extracted from the well-beaten gravel-walk
were kept separate from the others; and of these (59 in number) nearly
five times as many had been drawn in by the tip as by the base; whereas
of those extracted from the lawn and flower-bed, where from the soil
yielding more easily, less care would be necessary in plugging up the
burrows, the proportion of those drawn in by the tip (130) to those drawn
in by the base (48) was rather less than three to one. That these
petioles had been dragged into the burrows for plugging them up, and not
for food, was manifest, as neither end, as far as I could see, had been
gnawed. As several petioles are used to plug up the same burrow, in one
case as many as 10, and in another case as many as 15, the worms may
perhaps at first draw in a few by the thicker end so as to save labour;
but afterwards a large majority are drawn in by the pointed end, in order
to plug up the hole securely.
Public-domain text, read in full here on John Shaqi.
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