organs of flight are concerned, would
have converted the animal have converted the animal 1872 |
convert it 1859 1860 1861 1866 1869 |
into a bat. In
certain bats in which certain bats in which 1872 |
bats which have 1859 1860 1861 1866 |
certain bats which have 1869 |
the wing-membrane
extends extends 1872 | extended 1859 1860 1861 1866 1869 |
from the top of the shoulder to the
tail tail 1872 | tail, 1859 1860 1861 1866 1869 |
and includes and includes 1872 | including 1859 1860 1861 1866 1869 |
the hind-legs, we perhaps
see see 1859 1860 1861 1866 1872 |
yet see actual 1869 |
traces of an apparatus originally
fitted fitted 1869 1872 | constructed 1859 1860 1861 1866 |
for gliding through the air rather than for flight. |
|
If about a dozen genera of birds
were to were to 1872 | had 1859 1860 1861 1866 1869 |
become
extinct, extinct, 1872 | extinct 1859 1860 1861 1866 1869 |
...OMIT 1872 |
or were unknown, 1859 1860 1861 1866 1869 |
who would have ventured to
....... 1861 1866 1869 1872 | have 1859 1860 |
surmise surmise 1861 1866 1869 1872 | surmised 1859 1860 |
that birds might have existed which used their wings solely as flappers, like the logger-headed duck (Micropterus of Eyton); as fins in the water and
as front-legs as front-legs 1872 | front legs 1859 1860 1861 1866 1869 |
on the land, like the penguin; as sails, like the ostrich; and functionally for no purpose, like the
Apteryx? Apteryx? 1861 1866 1869 1872 | Apteryx. 1859 1860 |
Yet the structure of each of these birds is good for it, under the conditions of life to which it is exposed, for each has to live by a struggle; but it is not necessarily the best possible under all possible conditions. It must not be inferred from these remarks that any of the grades of wing-structure here alluded to, which perhaps may all
be the result of be the result of 1872 |
have resulted from 1859 1860 1861 1866 1869 |
disuse, indicate the
....... 1872 | natural 1859 1860 1861 1866 1869 |
steps by which birds
actually actually 1872 | have 1859 1860 1861 1866 1869 |
acquired their perfect power of flight; but they
serve serve 1872 | serve, 1859 1860 1861 1866 1869 |
to show what diversified means of transition are at least to show what diversified means of transition are at least 1872 |
at least, to show what diversified means of transition are 1859 1860 1861 1866 1869 |
possible. |
|
Seeing that a few members of such water-breathing classes as the Crustacea and Mollusca are adapted to live on the
land; land; 1860 1861 1866 1869 1872 | land, 1859 |
and seeing that we have flying birds and mammals, flying insects of the most diversified types, and formerly had flying reptiles, it is conceivable that flying-fish, which now glide far through the air, slightly rising and turning by the aid of their fluttering fins, might have been modified into perfectly winged animals. If this had been effected, who would have ever imagined that in an early transitional state they had been
the inhabitants the inhabitants 1869 1872 | inhabitants 1859 1860 1861 1866 |
of the open ocean, and had used their incipient organs of flight exclusively, as far as we know, to escape being devoured by other fish? |
|
When we see any structure highly perfected for any particular habit, as the wings of a bird for flight, we should bear in mind that animals displaying early
transitional transitional 1859 1869 1872 | tran- sitional 1860 1861 1866 |
grades of the structure will seldom
have survived to have survived to 1872 |
continue to exist to 1859 1860 1861 1866 |
exist at 1869 |
the present day, for they will have been supplanted by
their successors, which were gradually rendered more their successors, which were gradually rendered more 1869 1872 |
the very process of 1859 1860 1861 1866 |
perfect perfect 1869 1872 | perfection 1859 1860 1861 1866 |
through natural selection. Furthermore, we may conclude that
transitional transitional 1860 1861 1866 1869 1872 | transi- tional 1859 |
states states 1869 1872 | grades 1859 1860 1861 1866 |
between structures fitted for very different habits of life will rarely have been developed at an early period in great numbers and under many subordinate forms. Thus, to return to our imaginary illustration of the
flying-fish, flying-fish, 1859 1860 1861 1869 1872 | flying-fish; 1866 |
it does not seem probable that fishes capable of true flight would have been developed under many subordinate forms, for taking prey of many kinds in many ways, on the land and in the water, until their organs of flight
|