The Formation of Vegetable Mould Through the Action of Worms: With Observations on Their Habits — John Shaqi
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
The leaves of a foreign plant were next searched for, the blades of which
were not more pointed towards the apex than towards the base. This
proved to be the case with those of a laburnum (a hybrid between _Cytisus
alpinus_ and _laburnum_) for on doubling the terminal over the basal
half, they generally fitted exactly; and when there was any difference,
the basal half was a little the narrower. It might, therefore, have been
expected that an almost equal number of these leaves would have been
drawn in by the tip and base, or a slight excess in favour of the latter.
But of 73 leaves (not included in the first lot of 227) pulled out of
worm-burrows, 63 per cent. had been drawn in by the tip; 27 per cent. by
the base, and 10 per cent. transversely. We here see that a far larger
proportion, viz., 27 per cent. were drawn in by the base than in the case
of lime leaves, the blades of which are very broad at the base, and of
which only 4 per cent. had thus been drawn in. We may perhaps account
for the fact of a still larger proportion of the laburnum leaves not
having been drawn in by the base, by worms having acquired the habit of
generally drawing in leaves by their tips and thus avoiding the
foot-stalk. For the basal margin of the blade in many kinds of leaves
forms a large angle with the foot-stalk; and if such a leaf were drawn in
by the foot-stalk, the basal margin would come abruptly into contact with
the ground on each side of the burrow, and would render the drawing in of
the leaf very difficult.
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