| → as has been remarked by Owen, quicker 1866 1869 1872 |
| quicker 1861 |
|
| → Dr. Falconer, believes that it is chiefly insects which, 1866 1869 1872 |
| believes that at the present day insects (as Bruce has likewise described in Abyssinia), 1861 |
|
| → in India, check 1866 1869 1872 |
| are one chief check to 1861 |
|
| → increase; and this was Bruce's conclusion with respect to the African elephant in Abyssinia. 1866 1872 |
| increase. 1861 |
| increase; and this was Bruces conclusion with respect to the African elephant in Abyssinia. 1869 |
|
| → OMIT 1866 1869 1872 |
| of different kinds, 1861 |
|
|
from the analogy of all other mammals, even of the
elephant, and from the history of the naturalisation of the domestic horse in South America, that under more favourable conditions it would in a very few years have stocked the whole continent. But we could not have told what the unfavourable conditions were which checked its increase, whether some one or several contingencies, and at what period of the
life, and in what degree, they severally acted. If the conditions had gone on, however slowly, becoming less and less favourable, we assuredly should not have perceived the fact, yet the fossil horse would certainly have become rarer and rarer, and finally extinct;— its place being seized on by some more successful competitor. |
|
| It is most difficult always to remember that the increase of every
is constantly being checked by unperceived
agencies; and that these same unperceived agencies are amply sufficient to cause rarity, and finally extinction. So little is this subject understood, that I have heard surprise repeatedly expressed at such great monsters as the Mastodon and the more ancient Dinosaurians having become extinct; as if mere bodily strength gave victory in the battle of life. Mere size, on the contrary, would in some cases
→as has been remarked by Owen, quicker
extermination from the greater amount of requisite food. Before man inhabited India or Africa, some cause must have checked the continued increase of the existing elephant. A highly capable
→Dr. Falconer, believes that it is chiefly insects which,
from incessantly harassing and weakening the
→in India, check
its
→increase; and this was Bruce's conclusion with respect to the African elephant in Abyssinia. It is certain that insects
→OMIT
and blood-sucking
determine the existence of the larger naturalised quadrupeds in several parts of S.
We see in many cases in the more recent tertiary formations, that rarity precedes extinction; and we know that this has been the progress of events with those animals which have been exterminated, either locally or wholly, through
agency. I may repeat what I published in 1845, namely, that to admit that species generally become rare before they become extinct— to feel no surprise at the rarity of a species, and yet to marvel greatly when
ceases to exist, is much the same as to admit that sickness in the individual is the forerunner of death— to feel no surprise at sickness,
when the sick man dies, to wonder and to suspect that he died by some
deed of violence. |
|
| The theory of natural selection is grounded on the belief that each new variety, and ultimately each new species, is produced and
|
