Comparison with 1860 |
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rodents or new beasts of prey immigrate, or old ones become modified, and all analogy would lead us to believe that some at least of the squirrels would decrease in numbers or become exterminated, unless they also became modified and improved in structure in a corresponding manner. Therefore, I can see no difficulty, more especially under changing conditions of life, in the continued preservation of individuals with fuller and fuller flank-membranes, each modification being useful, each being propagated, until
by the accumulated effects of this process of natural selection, a perfect so-called flying squirrel was produced. |
|
Now look at the Galeopithecus or flying
lemur, which formerly was falsely
ranked amongst bats. It has an
extremely wide flank-membrane,
stretching
from the corners of the jaw to the tail, and including
the limbs and
the elongated fingers:
the
flank membrane
is, also, furnished with an extensor muscle. ↑1 blocks not present in 1859 1860 1861 1866 1869; present in 1872 | This flank-membrane is furnished with an extensor muscle.
|
Although no graduated links of structure,
fitted for gliding through the air, now connect the Galeopithecus with the other Lemuridæ,
yet I can see
no difficulty in supposing that such links formerly existed, and that each had been formed by
the same steps
as in
the case of the
less perfectly gliding squirrels; and that
each grade of structure had been
useful to its possessor. Nor can I see any insuperable difficulty in further believing it possible
that the membrane-connected
fingers and fore-arm
of the Galeopithecus might be
greatly lengthened by natural selection;
and this, as far as the organs of flight are concerned, would convert it
into a bat. In bats which have
the wing-membrane extended
from the top of the shoulder to the tail,
including
the hind-legs, we perhaps see
traces of an apparatus originally constructed
for gliding through the air rather than for flight.
|
rodents or new beasts of prey immigrate, or old ones become modified, and all analogy would lead us to believe that some at least of the squirrels would decrease in numbers or become exterminated, unless they also became modified and improved in structure in a corresponding manner. Therefore, I can see no difficulty, more especially under changing conditions of life, in the continued preservation of individuals with fuller and fuller flank-membranes, each modification being useful, each being propagated,
until until 1859 1860 1861 | until, 1866 1869 1872 |
by the accumulated effects of this process of natural selection, a perfect so-called flying squirrel was produced. |
|
Now look at the Galeopithecus or
flying flying 1859 1860 1861 1866 1869 | so-called flying 1872 |
lemur, which formerly was
falsely falsely 1859 1860 1861 1866 | falsely 1869 1872 |
ranked amongst
bats. bats. 1859 1860 1861 1866 1869 |
bats, but is now believed to belong to the Insectivora. 1872 |
It has an It has an 1859 1860 1861 1866 1869 |
An 1872 |
extremely wide
flank-membrane, flank-membrane, 1859 1860 1861 1866 1869 | flank-membrane 1872 |
stretching stretching 1859 1860 1861 1866 1869 | stretches 1872 |
from the corners of the jaw to the tail, and
including including 1859 1860 1861 1866 1869 | includes 1872 |
the limbs
and and 1859 1860 1861 1866 1869 | with 1872 |
the elongated
fingers: fingers: 1859 1860 1861 1866 1869 | fingers. 1872 |
the the 1859 1860 1861 1866 1869 | the 1872 |
flank-membrane flank-membrane 1860 1861 1866 1869 | flank-membrane 1872 | flank membrane 1859 |
is, is, 1859 1860 1861 1866 1869 | is, 1872 |
also, also, 1859 1860 1861 1866 1869 | also, 1872 |
furnished furnished 1859 1860 1861 1866 1869 | furnished 1872 |
with with 1859 1860 1861 1866 1869 | with 1872 |
an an 1859 1860 1861 1866 1869 | an 1872 |
extensor extensor 1859 1860 1861 1866 1869 | extensor 1872 |
muscle. muscle. 1859 1860 1861 1866 1869 | muscle. 1872 |
↑1 blocks not present in 1859 1860 1861 1866 1869; present in 1872 | This flank-membrane is furnished with an extensor muscle.
|
Although no graduated links of
structure, structure, 1859 1860 1861 1866 1872 | struc- ture, 1869 |
fitted for gliding through the air, now connect the Galeopithecus with the other
Lemuridæ, Lemuridæ, 1859 1860 1861 1866 1869 | Insectivora, 1872 |
yet
I see I see 1860 1861 1866 |
I can see 1859 |
there is 1869 1872 |
no difficulty in supposing that such links formerly existed, and that each
had been formed by had been formed by 1859 1860 1861 1866 1869 |
was developed in 1872 |
the same
steps steps 1859 1860 1861 1866 1869 | manner 1872 |
as
in in 1859 1860 1861 1866 1869 | with 1872 |
the
case of the case of the 1859 1860 1861 1866 1869 |
OMIT 1872 |
less perfectly gliding squirrels;
and that and that 1859 1860 1861 1866 1869 | and that 1872 |
each grade of structure
was was 1860 1861 1866 1869 | had been 1859 | having been 1872 |
useful to its possessor. Nor can I see any insuperable difficulty in further believing
it possible it possible 1859 1860 1861 1866 1869 | it possible 1872 |
that the
membrane-connected membrane-connected 1859 1860 1861 1866 1869 | membrane connected 1872 |
fingers and
forearm forearm 1860 1861 1866 1869 | fore-arm 1859 1872 |
of the Galeopithecus might
be be 1859 1860 1861 1866 1869 | have been 1872 |
greatly lengthened by natural
selection; selection; 1859 1860 1861 1866 1869 | selection. 1872 |
and this, as far as the organs of flight are concerned, would
convert it convert it 1859 1860 1861 1866 1869 |
have converted the animal 1872 |
into a bat. In
bats which have bats which have 1859 1860 1861 1866 |
certain bats which have 1869 |
certain bats in which 1872 |
the wing-membrane
extended extended 1859 1860 1861 1866 1869 | extends 1872 |
from the top of the shoulder to the
tail, tail, 1859 1860 1861 1866 1869 | tail 1872 |
including including 1859 1860 1861 1866 1869 | and includes 1872 |
the hind-legs, we perhaps
see see 1859 1860 1861 1866 1872 |
yet see actual 1869 |
traces of an apparatus originally
constructed constructed 1859 1860 1861 1866 | fitted 1869 1872 |
for gliding through the air rather than for flight.
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