| → lessen the number of the navel-frequenting flies— then cattle and horses would become feral, and this would certainly 1861 1866 1872 |
| certainly 1859 1860 |
| lessen the number of the navel-frequenting flies—then cattle and horses would become feral, and this would certainly 1869 |
|
| → 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 |
|
| → find from experiments 1861 1866 1869 1872 |
| have, also, reason to believe 1859 1860 |
|
| ↑ 1 blocks not present in 1861 1866 1869 1872; present in 1859 1860 |
| From experiments which I have tried,
I have found that the visits of bees,
if not indispensable, are at least highly beneficial to
the fertilisation of our
clovers;
but humble-bees alone visit the common
red clover (Trifolium pratense), as other bees cannot reach the nectar.
|
|
| →lessen the number of the navel-frequenting flies— then cattle and horses would become feral, and this would certainly
greatly alter (as indeed I have observed in parts of South America) the vegetation: this again would largely affect the insects; and this, as we
seen in
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
nature the relations
ever be as simple as this. Battle within battle must
be
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
give the victory to one organic being over another.
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,
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
→in this part of England,
is never visited
→by
insects, and consequently, from its peculiar structure, never
a seed.
our orchidaceous plants absolutely require the visits of
to remove their pollen-masses and thus to fertilise them. I
→find from experiments
that humble-bees are
to the fertilisation of the heartsease (Viola tricolor), for other bees do not visit this flower. ↑
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
but 20 other heads protected from bees produced not one. Again, 100 heads of red clover (T. pratense)
|
