| ↑ 1 blocks not present in 1860 1861 1866 1869 1872; present in 1859 |
| The face of Nature may be compared to a yielding surface, with ten thousand sharp wedges packed close together and driven inwards by incessant blows, sometimes one wedge being struck, and then another with greater force.
|
|
| ←Subtitle not present 1859 1860 1861
Nature
of
the
Checks
to
Increase. 1866 1869 1872 |
| → The causes which 1860 1861 1866 1869 1872 |
| What 1859 |
|
| → in number are 1860 1861 |
| in number is 1859 |
| are 1866 1869 1872 |
|
| → has 1859 1860 1861 1866 1869 |
| of the checks to increase has 1872 |
|
| → discuss some of the checks 1859 1860 1861 1866 1869 |
| to discuss it 1872 |
|
| → I believe that it is 1859 1860 1861 1866 1869 |
| it appears that 1872 |
|
|
its life; that heavy destruction inevitably falls either on the young or old, during each generation or at recurrent intervals. Lighten any check, mitigate the destruction ever so little, and the number of the species will almost instantaneously increase to any amount. ↑
→
|
|
→The causes which
the natural tendency of each species to increase
→in number are
most obscure. Look at the most vigorous species; by as much as it swarms in numbers, by so much will
to increase
still
We know not exactly what the checks are
even
single instance. Nor will this surprise any one who reflects how ignorant we are on this head, even in regard to mankind,
incomparably better known than any other animal. This subject
→has
been ably treated by several authors, and I
in
future
→discuss some of the checks
at considerable length, more especially in regard to the feral animals of South America. Here I will make only a few remarks, just to recall to the
mind some of the chief points. Eggs or very young animals seem generally to suffer most, but this is not invariably the case. With plants there is a vast destruction of seeds, but, from some observations which I have
→I believe that it is
the seedlings
suffer most from germinating in ground already thickly stocked with other plants. Seedlings, also, are destroyed in vast numbers by various enemies; for instance, on a piece of ground three feet long and two wide, dug and cleared, and where there could be no choking from other plants, I marked all the seedlings of our native weeds as they came up, and out of
357 no less than
were destroyed, chiefly by slugs and insects. If turf which has long been mown, and the case would be the same with turf closely browsed by quadrupeds, be let to grow, the more vigorous plants
|
