| → certain mammals or of the whole class 1861 1866 |
| the whole class of mammals, or of certain members in this class, 1869 1872 |
|
| → of, and thus exterminating, 1861 1866 1869 |
| of 1872 |
|
| → compared with fishes. 1861 1866 |
| in comparison with fishes. 1869 |
| in having to come continually to the surface to breathe. 1872 |
|
| ↑ 1 blocks not present in 1859 1860 1861 1866; present in 1869 1872 |
| In this latter class,
members of the shark family would not tend to supplant the lancelet; for the lancelet, as I hear from Fritz Müller,
has as sole companion and competitor on the barren sandy shore of South Brazil, an anomalous annelid.
|
|
| → they have existed in 1861 1866 |
| their 1869 1872 |
|
| → which, as already explained, 1861 1866 |
| have 1869 1872 |
|
| → and in nearly every class, 1861 1866 |
| OMIT 1869 1872 |
|
| → favourable variations 1861 1866 |
| variations or individual differences of a favourable nature 1869 |
| variations or individual differences of a favorable nature 1872 |
|
|
invertebrate classes. But mammals and fish hardly come into competition with each other; the advancement of
→certain mammals or of the whole class
to the highest grade
would not lead to their taking the place
→of, and thus exterminating,
fishes. Physiologists believe that the brain must be bathed by warm blood to be highly active, and this requires
respiration; so that warm-blooded mammals when inhabiting the water
under
→compared with fishes. In this latter class, members of the shark family would not, it is probable, tend to supplant the
the struggle for existence in the case of the
apparently will lie with members of the invertebrate classes. ↑
The three lowest orders of mammals, namely, marsupials, edentata, and rodents, co-exist in South America in the same region with numerous monkeys, and probably interfere little with each other. Although organisation, on the whole, may have advanced and be
throughout the world, yet the scale will
present
degrees of perfection; for the high advancement of certain whole classes, or of certain members of each class, does not at all necessarily lead to the extinction of those groups with which they do not enter into close competition. In some cases, as we shall hereafter see, lowly organised forms
to have been preserved to the present
from inhabiting
or
stations, where they have been subjected to less severe competition, and where
→they have existed in
scanty
→which, as already explained,
the chance of
variations arising. |
|
| Finally, I believe that
organised forms now exist
throughout the world,
→and in nearly every class,
from various causes. In some cases
→favourable variations
may never have arisen for natural
|
