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OriginOfSpecies - 475 Rows
Column Type #Values Column Stats
id int(11) 475 Column Stats
subject varchar(80) 14 Column Stats
title varchar(250) 139 Column Stats
ordinal int(11) 30 Column Stats
description text 474 Column Stats

475 rows, page 45 of 119 (4/p)
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Export to Excel select * from OriginOfSpecies order by subject limit 176, 4 (Page 45: Row)
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description
04 - Natural Selection 04-12 - On the Degree to which Organisation tends to advance 50 Whether organisation on the whole has actually advanced from the remotest geological periods to the present day will be more conveniently discussed in our chapter on Geological Succession.

But it may be objected that if all organic beings thus tend to rise in the scale, how is it that throughout the world a multitude of the lowest forms still exist; and how is it that in each great class some forms are far more highly developed than others?

Why have not the more highly developed forms everywhere supplanted and exterminated the lower?

Lamarck, who believed in an innate and inevitable tendency towards perfection in all organic beings, seems to have felt this difficulty so strongly, that he was led to suppose that new and simple forms are continually being produced by spontaneous generation.
04 - Natural Selection 04-12 - On the Degree to which Organisation tends to advance 60 Science has not as yet proved the truth of this belief, whatever the future may reveal.

On our theory the continued existence of lowly organisms offers no difficulty; for natural selection, or the survival of the fittest, does not necessarily include progressive 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 earthworm, to be highly organised.

earthworm
earthworm


If it were no advantage, these forms would be left, by natural selection, unimproved or but little improved, and might remain for indefinite ages in their present lowly 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.

rhizopod
rhizopod
04 - Natural Selection 04-12 - On the Degree to which Organisation tends to advance 70 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; 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 different grades of organisation within the same great group; for instance, in the vertebrata, to the co-existence of mammals and fish- amongst mammalia, to the coexistence of man and the Ornithorhynchus- amongst fishes, to the co-existence of the shark and the lancelet (Amphioxus), which latter fish in the extreme simplicity of its structure approaches the invertebrate classes.

Ornithorhynchus
Ornithorhynchus

shark
shark

lancelet
lancelet
04 - Natural Selection 04-12 - On the Degree to which Organisation tends to advance 80 But mammals and fish hardly come into competition with each other; the advancement of the whole class of mammals, or of certain members in this class, to the highest grade would not lead to their taking the place of fishes.

Physiologists believe that the brain must be bathed by warm blood to be highly active, and this requires aerial respiration; so that warm-blooded mammals when inhabiting the water lie under a disadvantage in having to come continually to the surface to breathe. With fishes, members of the shark family would not tend to supplant the lancelet; for the lancelet, as I hear from Fritz Muller, has as sole companion and competitor on the barren sandy shore of South Brazil, an anomalous annelid.

annelid
annelid