        item: #1 of 15
          id: chapter_000
      author: None
       title: chapter_000
        date: None
       words: 1719
      flesch: 49
     summary: In considering the Origin of Species, it is quite conceivable that a naturalist, reflecting on the mutual affinities of organic beings, on their embryological relations, their geographical distribution, geological succession, and other such facts, might come to the conclusion that each species had not been independently created, but had descended, like varieties, from other species. These facts seemed to me to throw some light on the origin of species--that mystery of mysteries, as it has been called by one of our greatest philosophers.
    keywords: beings; chapter; conclusions; conditions; facts; relations; species; subject; variation; work
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        item: #2 of 15
          id: chapter_001
      author: None
       title: chapter_001
        date: None
       words: 11912
      flesch: 49
     summary: When in any country several domestic breeds have once been established, their occasional intercrossing, with the aid of selection, has, no doubt, largely aided in the formation of new sub-breeds; but the importance of the crossing of varieties has, I believe, been greatly exaggerated, both in regard to aniggerated, both in regard to animals and to those plants which are propagated by seed. When we bear in mind that Britain has now hardly one peculiar mammal, and France but few distinct from those of Germany and conversely, and so with Hungary, Spain, &c., but that each of these kingdoms possesses several peculiar breeds of cattle, sheep, &c., we must admit that many domestic breeds have originated in Europe; for whence could they have been derived, as these several countries do not possess a number of peculiar species as distinct parent-stocks?
    keywords: animals; breeds; cases; characters; conditions; degree; differences; different; distinct; domestic; domestic breeds; doubt; feathers; generations; great; importance; individuals; instance; large; life; like; long; man; nature; number; parent; pigeons; plants; races; rock; selection; sheep; size; slight; species; state; structure; sub; variability; varieties; wild
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        item: #3 of 15
          id: chapter_002
      author: None
       title: chapter_002
        date: None
       words: 4937
      flesch: 47
     summary: For instance, Mr. H. C. Watson has marked for me in the well-sifted London Catalogue of plants (4th edition) 63 plants which are therein ranked as species, but which he considers as so closely allied to other species as to be of doubtful value: these 63 reputed species range on an average over 6.9 of the provinces into which Mr. Watson has divided Great Britain. Species very closely allied to other species apparently have restricted ranges.
    keywords: country; differences; different; doubtful; forms; genera; genus; important; larger; naturalists; number; plants; rank; species; variation; varieties; variety
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        item: #4 of 15
          id: chapter_003
      author: None
       title: chapter_003
        date: None
       words: 6237
      flesch: 53
     summary: When we travel southward and see a species decreasing in numbers, we may feel sure that the cause lies quite as much in other species being favoured, as in this one being hurt. That climate acts in main part indirectly by favouring other species, we may clearly see in the prodigious number of plants in our gardens which can perfectly well endure our climate, but which never become naturalised, for they cannot compete with our native plants nor resist destruction by our native animals.
    keywords: animals; beings; birds; cases; climate; destruction; different; eggs; existence; food; increase; individuals; life; nature; number; organic; plants; seeds; species; struggle; varieties; years; young
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        item: #5 of 15
          id: chapter_004
      author: None
       title: chapter_004
        date: None
       words: 15919
      flesch: 44
     summary: At each period of growth all the growing twigs have tried to branch out on all sides, and to overtop and kill the surrounding twigs and branches, in the same manner as species and groups of species have tried to overmaster other species in the great battle for life. Lastly, isolation, by checking immigration and consequently competition, will give time for any new variety to be slowly improved; and this may sometimes be of importance in the production of new species.
    keywords: animals; area; better; case; chance; character; conditions; country; descendants; diagram; different; distinct; flower; forms; genera; genus; great; groups; individuals; inhabitants; insects; large; life; long; man; modification; modified; natural; natural selection; nature; new; new species; number; organic; places; plants; pollen; process; selection; small; species; structure; tree; variations; varieties; variety
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        item: #6 of 15
          id: chapter_005
      author: None
       title: chapter_005
        date: None
       words: 12441
      flesch: 44
     summary: The fact of varieties of one species, when they range {133} into the zone of habitation of other species, often acquiring in a very slight degree some of the characters of such species, accords with our view that species of all kinds are only well-marked and permanent varieties. The opercular valves of sessile cirripedes (rock barnacles) are, in every sense of the word, very important structures, and they differ extremely little even in different genera; but in the several species of one genus, Pyrgoma, these valves present a marvellous amount of diversification: the homologous valves in the different species being sometimes wholly unlike in shape; and the amount of variation in the individuals of several of the species is so great, that it is no exaggeration to state that the varieties differ more from each other in the characters of these important valves than do other species of distinct genera.
    keywords: analogous; animals; breeds; case; characters; climate; common; conditions; degree; differences; different; disuse; domestic; generations; genus; horse; legs; life; long; manner; natural; natural selection; nature; organisation; parts; period; plants; secondary; selection; sexual; shoulder; species; specific; state; stripes; structure; tendency; variability; variable; variation; varieties; view
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        item: #7 of 15
          id: chapter_006
      author: None
       title: chapter_006
        date: None
       words: 11201
      flesch: 41
     summary: Natural selection will never produce in a being anything injurious to itself, for natural selection acts solely by and for the good of each. But natural selection can and does often produce structures for the direct injury of other species, as we see in the fang of the adder, and in the ovipositor of the ichneumon, by which its eggs are {201} deposited in the living bodies of other insects.
    keywords: advantage; animals; case; conditions; continuous; country; different; difficulty; eye; forms; good; habits; having; intermediate; life; like; little; long; modification; modified; natural; natural selection; nature; new; numbers; organs; perfect; perfection; place; possible; process; selection; species; structure; theory; time; transitional; use; varieties
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        item: #8 of 15
          id: chapter_007
      author: None
       title: chapter_007
        date: None
       words: 12131
      flesch: 48
     summary: Hence it would continually be more and more advantageous to our humble-bee, if she were to make her cells more and more regular, nearer together, and aggregated into a mass, like the cells of the Melipona; for in this case a large part of the bounding surface of each cell would serve to bound other cells, and much wax would be saved. Instincts comparable with habits, but different in their origin--Instincts graduated--Aphides and ants--Instincts variable--Domestic instincts, their origin--Natural instincts of the cuckoo, ostrich, and parasitic bees--Slave-making-ants--Hive-bee, its cell-making instinct--Difficulties on the theory of the Natural Selection of instincts--Neuter or sterile insects--Summary.
    keywords: ants; bees; birds; case; cells; comb; community; cuckoo; different; difficulty; domestic; eggs; habit; hive; huber; instincts; large; little; making; masters; natural; natural selection; nature; nest; proper; selection; slaves; species; spheres; sterile; structure; theory; time; wall; wax; work; workers; young
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        item: #9 of 15
          id: chapter_008
      author: None
       title: chapter_008
        date: None
       words: 10125
      flesch: 44
     summary: Although the plants in these experiments appeared perfectly healthy, and although both the ovules and pollen of the same flower were perfectly good with respect to other species, yet as they were functionally imperfect in their mutual self-action, we must infer that the plants were in an unnatural state. Several other singular rules could be given from Grtner: for instance, some species have a remarkable power of crossing with other species; other species of the same genus have a remarkable power of impressing their likeness on their hybrid offspring; but these two powers do not at all necessarily go together.
    keywords: animals; case; certain; conditions; crossed; degree; differences; different; distinct; distinct species; facility; facts; fertile; fertility; grtner; hybrids; instance; nature; offspring; parent; plants; pollen; pure; reproductive; species; sterile; sterility; varieties
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        item: #10 of 15
          id: chapter_009
      author: None
       title: chapter_009
        date: None
       words: 10054
      flesch: 44
     summary: This group includes the large majority of existing species. In a memoir on Fossil Sessile Cirripedes, I have stated that, from the {305} number of existing and extinct tertiary species; from the extraordinary abundance of the individuals of many species all over the world, from the Arctic regions to the equator, inhabiting various zones of depths from the upper tidal limits to 50 fathoms; from the perfect manner in which specimens are preserved in the oldest tertiary beds; from the ease with which even a fragment of a valve can be recognised; from all these circumstances, I inferred that had sessile cirripedes existed during the secondary periods, they would certainly have been preserved and discovered; and as not one species had then been discovered in beds of this age, I concluded that this great group had been suddenly developed at the commencement of the tertiary series.
    keywords: america; area; beds; europe; feet; formation; forms; fossil; geological; great; instance; intermediate; land; life; links; long; new; period; present; rate; record; remains; sea; sediment; silurian; species; strata; subsidence; tertiary; theory; thickness; time; varieties; world; years
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        item: #11 of 15
          id: chapter_010
      author: None
       title: chapter_010
        date: None
       words: 10516
      flesch: 43
     summary: Thus, as it seems to me, the parallel, and, taken in a large sense, simultaneous, succession of the same forms of life throughout the world, accords well with the principle of new species having been formed by dominant species spreading widely and varying; the new species thus produced being themselves dominant owing to inheritance, and to having already had some advantage over their parents or over other species; these again spreading, varying, and producing new species. On the slow and successive appearance of new species--On their different rates of change--Species once lost do not reappear--Groups of species follow the same general rules in their appearance and disappearance as do single species--On Extinction--On simultaneous changes in the forms of life throughout the world--On the affinities of extinct species to each other and to living species--On the state of development of ancient forms--On the succession of the same types within the same areas--Summary of preceding and present chapters.
    keywords: america; ancient; character; degree; distinct; existing; extinct; extinction; families; formations; forms; genera; geological; great; groups; inhabitants; intermediate; intervals; life; living; long; modified; new; new species; number; old; period; present; species; succession; theory; time; world
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        item: #12 of 15
          id: chapter_011
      author: None
       title: chapter_011
        date: None
       words: 11542
      flesch: 47
     summary: On the southern mountains of Australia, Dr. F. Mller has discovered several European species; other species, not introduced by man, occur on the lowlands; and a long list can be given, as I am informed by Dr. Hooker, of European genera, found in Australia, but not in the intermediate torrid regions. But the geographical and climatal changes, which have certainly occurred within recent geological times, must have interrupted or rendered discontinuous the {354} formerly continuous range of many species.
    keywords: america; arctic; climate; conditions; continent; days; distant; distinct; distribution; europe; facts; far; forms; glacial; great; inhabitants; islands; land; long; means; migration; modification; mountains; new; northern; old; period; plants; points; present; productions; regions; sea; seeds; southern; species; temperate; time; world
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        item: #13 of 15
          id: chapter_012
      author: None
       title: chapter_012
        date: None
       words: 8807
      flesch: 43
     summary: This relation between the power and extent of migration of a species, either at the present time or at some former period under different physical conditions, and the existence at remote points of the world of other species allied to it, is shown in another and more general way. I have carefully searched the oldest voyages, but have not finished my search; as yet I have not found a single {394} instance, free from doubt, of a terrestrial mammal (excluding domesticated animals kept by the natives) inhabiting an island situated above 300 miles from a continent or great continental island; and many islands situated at a much less distance are equally barren.
    keywords: archipelago; birds; conditions; continent; different; distant; distinct; endemic; facts; forms; fresh; galapagos; great; inhabitants; islands; mammals; means; modified; new; oceanic; plants; range; relation; sea; seeds; shells; species; time; view; water; world
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        item: #14 of 15
          id: chapter_013
      author: None
       title: chapter_013
        date: None
       words: 14903
      flesch: 43
     summary: Extinction has only separated groups: it has by no means made them; for if every form which has ever lived on this earth were suddenly to reappear, though it would be quite impossible to give definitions by which each group could be distinguished from other groups, as all would blend together by steps as fine as those between the finest existing varieties, nevertheless a natural classification, or at least a natural arrangement, would be possible. And in some whole groups of animals and in certain members of other groups, the embryo does not at any period differ widely from the {442} adult: thus Owen has remarked in regard to cuttle-fish, there is no metamorphosis; the cephalopodic character is manifested long before the parts of the embryo are completed; and again in spiders, there is nothing worthy to be called a metamorphosis.
    keywords: affinities; age; animals; case; certain; characters; classification; common; descendants; descent; different; distinct; early; embryo; forms; genera; genus; great; groups; habits; importance; instance; life; long; members; modification; modified; natural; naturalists; nature; number; organs; parent; parts; period; principle; rudimentary; selection; species; structure; system; value; varieties; view
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        item: #15 of 15
          id: chapter_014
      author: None
       title: chapter_014
        date: None
       words: 9831
      flesch: 45
     summary: The closely allied species also of the larger genera apparently have restricted ranges, and in their affinities they are clustered in little groups round other species--in which respects they resemble varieties. On this same {470} view we can understand how it is that in each region where many species of a genus have been produced, and where they now flourish, these same species should present many varieties; for where the manufactory of species has been active, we might expect, as a general rule, to find it still in action; and this is the case if varieties be incipient species.
    keywords: animals; beings; characters; common; conditions; creation; degree; descent; different; facts; forms; genus; great; groups; intermediate; life; long; means; modification; natural; naturalists; nature; new; number; organic; period; present; selection; slight; species; successive; theory; time; varieties; view; world
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