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1859
1860
1861
1866
1869
1872

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1861
1869
1872

1 blocks not present in 1859 1860 1861 1866; present in 1869 1872
Science has not as yet proved the truth of this belief, whatever the future may reveal.

includes no necessary and universal law of advancement or 1861 1866
or the survival of the fittest, does not necessarily include progressive 1869 1872

great existing differences in the 1861 1866
different 1869 1872

which occur within almost every 1861 1866
within each 1869
within the same 1872

co-existence 1861 1866
vertebrata, to the co-existence 1869 1872

fish in the vertebrata,— 1861 1866
fish— amongst mammalia, 1869 1872

mammalia— or 1861 1866
fishes, to the co-existence 1869 1872

lancelet (Branchiostoma), 1866 1869
amphioxus, 1861
the lancelet (Amphioxus), 1872

in all organic beings, seems to have felt this difficulty so strongly, that he was led to suppose that new and simple forms
are
were
continually being produced by spontaneous generation. I need hardly say that Science in her present state does not countenance the belief that living creatures are now ever produced from inorganic matter. On
our
my
theory the
continued
present
existence of lowly
organisms
organised
productions
productions
offers no difficulty; for natural
selection,
selection
includes no necessary and universal law of advancement or development— it only takes advantage of such variations as arise and are beneficial to each creature under its complex relations of life. And it may be asked what advantage, as far as we can see, would it be to an infusorian animalcule— to an intestinal worm— or even to an earth-worm, to be highly
organised.
organised?
If it were no advantage, these forms would be
left,
left
by natural
selection,
selection
unimproved or but little
improved:
improved,
improved;
and might remain for indefinite ages in their present
lowly
little advanced
condition. And geology tells us that some of the lowest forms, as the infusoria and rhizopods, have remained for an enormous period in nearly their present state. But to suppose that most of the many now existing low forms have not in the least advanced since the first dawn of life would be
extremely rash;
rash;
for every naturalist who has dissected some of the beings now ranked as very low in the scale, must have been struck with their really wondrous and beautiful organisation.
Nearly the same remarks are applicable if we look to the great existing differences in the grades of organisation which occur within almost every great group; for instance,
in
to
the co-existence of mammals and fish in the vertebrata,— to the co-existence of man and the
ornithorhynchus—
ornithorhynchus
amongst mammalia— or of the shark and lancelet (Branchiostoma), which latter fish in the extreme simplicity of its structure
closely
....
approaches the