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1859
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uniform for long periods of time, 1859 1860 1861 1866 1869
for long periods of time uniform, 1872

in this part of England, 1859 1860 1861 1866 1869
OMIT 1872

by 1859 1860 1861 1866 1869
in my garden by 1872

have, also, reason to believe 1859 1860
find from experiments 1861 1866 1869 1872

if not indispensable, are at least highly beneficial to 1859
are necessary for 1860

our 1859
some kinds of 1860

4 blocks not present in 1859 1860; present in 1861 1866 1869 1872
I have also found that the visits of bees are necessary for the fertilisation of some kinds of clover: for instance, 20 heads of Dutch clover (Trifolium repens) yielded 2,290 seeds; but 20 other heads protected from bees produced not one. Again, 100 heads of red clover (T. pratense) produced 2,700 seeds, but the same number of protected heads produced not a single seed. Humble-bees alone visit red clover, as other bees cannot reach the nectar. It has been suggested that moths may serve to fertilise the clovers; but I doubt this in the case of the red clover, from their weight being apparently not sufficient to depress the wing-petals.

I have very little doubt, 1859 1860
we may infer as highly probable 1861 1866 1869 1872

indeed I have observed in parts of South America) the vegetation: this again would largely affect the insects; and this, as we
have just
just have
seen in
Stafford-shire,
Staffordshire,
the insectivorous birds, and so onwards in ever-increasing circles of complexity. We began this series by insectivorous birds, and we have ended with them. Not that
under
in
nature the relations
will
can
ever be as simple as this. Battle within battle must
ever
ever
be
continually recurring
recurring
with varying success; and yet in the long-run the forces are so nicely balanced, that the face of nature remains uniform for long periods of time, though assuredly the merest trifle would
often
often
give the victory to one organic being over another.
Nevertheless,
Nevertheless
so profound is our ignorance, and so high our presumption, that we marvel when we hear of the extinction of an organic being; and as we do not see the cause, we invoke cataclysms to desolate the world, or invent laws on the duration of the forms of life!
I am tempted to give one more instance showing how plants and animals,
most
most
remote in the scale of nature, are bound together by a web of complex relations. I shall hereafter have occasion to show that the exotic Lobelia
fulgens
fulgens,
in this part of England, is never visited by insects, and consequently, from its peculiar structure, never
can
can
sets
set
a seed.
Nearly all
Many of
our orchidaceous plants absolutely require the visits of
insects
moths
to remove their pollen-masses and thus to fertilise them. I have, also, reason to believe that humble-bees are
almost indispensable
indispensable
to the fertilisation of the heartsease (Viola tricolor), for other bees do not visit this flower. From experiments which I have
lately tried,
tried,
I have found that the visits of
bees
bees,
if not indispensable, are at least highly beneficial to the fertilisation of our
clover;
clovers;
but humble-bees alone visit the
common
common
red clover (Trifolium pratense), as other bees cannot reach the nectar. Hence I have very little doubt,
that,
that
if the whole genus of humble-bees became