lead to the belief that
....... 1866 1869 1872 | formerly 1859 1860 1861 |
most fishes
formerly possessed formerly possessed 1866 1869 1872 | had 1859 1860 1861 |
electric organs, which
....... 1866 1869 1872 | most of 1859 1860 1861 |
their modified descendants have
now lost. now lost. 1866 1869 1872 |
lost. The presence of luminous organs in a few insects, belonging to different families and orders, offers a parallel case of difficulty. 1859 1860 1861 |
But when we look
at at 1869 1872 | closer to 1866 |
the
subject subject 1869 1872 | subject, 1866 |
more closely, we more closely, we 1869 1872 |
we 1866 |
find in the several fishes provided with electric
organs organs 1866 1869 | organs, 1872 |
that these are situated in different parts of the
body,—that body,—that 1866 1869 | body,— 1872 |
they they 1866 1869 | that they 1872 |
differ in construction, as in the arrangement of the plates, and, according to Pacini, in the process or means by which the electricity is
excited—and excited—and 1869 | excited,—and 1866 | excited— and 1872 |
lastly, in
the requisite nervous power the requisite nervous power 1866 1869 |
being supplied with nerves proceeding from different sources, 1872 |
being supplied through different nerves from widely different sources, and this is perhaps the most important of all the differences. being supplied through different nerves from widely different sources, and this is perhaps the most important of all the differences. 1869 |
(and this is perhaps the most important of all the differences) being supplied through different nerves from widely different sources. 1866 |
and this is perhaps the most important of all the differences. 1872 |
Hence in the several
remotely allied remotely allied 1866 1869 | remotely allied 1872 |
fishes furnished with electric organs, these cannot be considered as homologous, but only as analogous in function. Consequently there is no reason to suppose that they have been inherited from a common progenitor; for had this been the case they would have closely resembled each other in all respects. Thus the
greater greater 1866 1869 | greater 1872 |
difficulty
disappears, disappears, 1866 1869 |
of an organ, apparently the same, arising in several remotely allied species, disappears, 1872 |
leaving only the lesser yet still great difficulty; namely, by what graduated steps these organs have
arisen and arisen and 1866 1869 | arisen and 1872 |
been developed in each separate
group of fishes.
group of fishes.
1869 |
fish.
1866 |
group of fishes.
1872 |
↑1 blocks not present in 1866 1869 1872; present in 1859 1860 1861 | The presence of luminous organs in a few insects, belonging to different families and orders, offers a parallel case of difficulty.
|
The luminous organs which occur
only
in a few insects, belonging to widely different
families families 1866 1869 | families, 1872 |
and
orders, and orders, and 1869 | orders, but 1866 | orders, and 1872 |
which are situated in different parts of
the body, the body, 1869 1872 | their bodies, 1866 |
offer offer 1866 1869 | offer, 1872 |
a a 1866 1869 |
under our present state of ignorance, a 1872 |
difficulty almost exactly parallel with that of the electric organs.
Other cases could be given; for instance in plants, the very curious contrivance of a mass of pollen-grains, borne on a foot-stalk with an adhesive gland, is apparently Other cases could be given; for instance in plants, the very curious contrivance of a mass of pollen-grains, borne on a foot-stalk with an adhesive gland, is apparently 1866 1869 |
In all these cases of two very distinct species furnished with apparently 1859 1860 1861 |
Other similar cases could be given; for instance in plants, the very curious contrivance of a mass of pollen-grains, borne on a foot-stalk with an adhesive gland, is apparently 1872 |
the same
in Orchis and Asclepias,—genera almost as remote as is possible amongst flowering plants. in Orchis and Asclepias,—genera almost as remote as is possible amongst flowering plants. 1866 1869 |
anomalous organ, it should be observed that, although the general appearance and function of the organ may be the same, yet some fundamental difference can generally be detected. 1859 1860 1861 |
in Orchis and Asclepias,— genera almost as remote as is possible amongst flowering plants; but here again the parts are not homologous. 1872 |
In all such cases of two species, far removed from each other in the scale of organisation, being furnished with similar anomalous organs, it should be observed that although the general appearance and function of the organ may be In all such cases of two species, far removed from each other in the scale of organisation, being furnished with similar anomalous organs, it should be observed that although the general appearance and function of the organ may be 1869 |
I am inclined to believe that in nearly the same way as two men have sometimes independently hit on the very same invention, so natural selection, working for the good of each being and taking advantage of analogous variations, has sometimes modified in very nearly 1859 1860 1861 |
In all these cases of two species, far removed from each other in the scale of organisation, being furnished with a similar anomalous organ, it should be observed that although the general appearance and function of the organ may be 1866 |
In all cases of beings, far removed from each other in the scale of organisation, which are furnished with similar and peculiar organs, it will be found that although the general appearance and function of the organs may be 1872 |
|