Darwinism: An Exposition of the Theory of Natural Selection with Some of Its ApplicationsMacmillan, 1901 |
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Página 23
... vegetation . In one of these ' secas , ' at the time of my visit , no less than 50,000 head of oxen and sheep and horses perished from starvation and thirst , after tearing deep out of the soil every trace of vegetation , including the ...
... vegetation . In one of these ' secas , ' at the time of my visit , no less than 50,000 head of oxen and sheep and horses perished from starvation and thirst , after tearing deep out of the soil every trace of vegetation , including the ...
Página 28
... vegetation . Some American plants , like the cotton - weed ( Asclepias curassavica ) , have now become common weeds over a large portion of the tropics . White clover ( Trifolium repens ) spreads over all the temperate regions of the ...
... vegetation . Some American plants , like the cotton - weed ( Asclepias curassavica ) , have now become common weeds over a large portion of the tropics . White clover ( Trifolium repens ) spreads over all the temperate regions of the ...
Página 29
... alter the character of the vegetation up to an elevation of 3000 feet . This is the Lantana mixta , a verbenaceous plant introduced from the West Indies , which appears to have found II 29 THE STRUGGLE FOR EXISTENCE 29.
... alter the character of the vegetation up to an elevation of 3000 feet . This is the Lantana mixta , a verbenaceous plant introduced from the West Indies , which appears to have found II 29 THE STRUGGLE FOR EXISTENCE 29.
Página 30
... vegetation where it becomes established . Great Fertility not essential to Rapid Increase . The not uncommon circumstance of slow - breeding animals being very numerous , shows that it is usually the amount of destruction which an ...
... vegetation where it becomes established . Great Fertility not essential to Rapid Increase . The not uncommon circumstance of slow - breeding animals being very numerous , shows that it is usually the amount of destruction which an ...
Página 35
... vegetation . In the tropical and all the warm temperate parts of the earth , where there is a sufficient supply of moisture , the forests present the same variety of species as does the turf of our old pastures ; and in the equatorial ...
... vegetation . In the tropical and all the warm temperate parts of the earth , where there is a sufficient supply of moisture , the forests present the same variety of species as does the turf of our old pastures ; and in the equatorial ...
Outras edições - Ver tudo
Darwinism: An Exposition of the Theory of Natural Selection, with Some of ... Alfred Russel Wallace Visualização integral - 1891 |
Darwinism: An Exposition of the Theory of Natural Selection, with Some of ... Alfred Russel Wallace Visualização integral - 1912 |
Darwinism: An Exposition of the Theory of Natural Selection, with Some of ... Alfred Russel Wallace Visualização integral - 1901 |
Palavras e frases frequentes
abundant adapted adduced allied species America amount animals and plants appears birds breed brilliant butterflies carnivora cause characters climate closely allied colours of animals common conspicuous continued cross-fertilisation crossed curious Darwin dicotyledons distinct species domestic animals effects eggs enemies Eocene evidence explained extinct facts faculty favourable female fertile fertilised flowers genera genus geological groups habits hybrids important increase individuals infertility insects intercrossing kind large number larvæ less living male mammalia mammals markings marsupials mimicry Miocene mode modified moths natural selection naturalists nests occur offspring organs Origin of Species peculiar pigeons Pliocene pollen portion possess probably produced Professor proportion protectively coloured pupa regions remarkable resemblance seeds self-fertilisation Silurian specimens spots sterility structure struggle for existence supposed surface tail theory tints tion toes trees tropical usually variability variation varied varieties vegetation warning colours whole wild wings Zealand
Passagens conhecidas
Página 335 - FLOWER in the crannied wall, I pluck you out of the crannies, I hold you here, root and all, in my hand, Little flower — but if I could understand What you are, root and all, and all in all, I should know what God and man is.
Página 130 - Nevertheless, I did not formerly consider sufficiently the existence of structures, which, as far as we can at present judge, are neither beneficial nor injurious; and this I believe to be one of the greatest oversights as yet detected in my work.
Página 476 - That life is not as idle ore, But iron dug from central gloom, And heated hot with burning fears, And dipt in baths of hissing tears, And batter'd with the shocks of doom To shape and use.
Página 38 - When we reflect on this struggle, we may console ourselves with the full belief, that the war of nature is not incessant, that no fear is felt, that death is generally prompt, and that the vigorous, the healthy, and the happy survive and multiply.
Página 410 - I have now recapitulated the facts and considerations which have thoroughly convinced me that species have been modified during a long course of descent. This has been effected chiefly through the natural selection of numerous successive, slight, favourable variations; aided in an important manner by the inherited effects of the use and disuse of parts; and in an unimportant manner, that is in relation to adaptive structures, whether past or present, by the direct action of external conditions, and...
Página 36 - Starting, and looking half round, I saw the lion just in the act of springing upon me. I was upon a little height ; he caught my shoulder as he sprang, and we both came to the ground below together. Growling horribly close to my ear, he shook me as a terrier dog does a rat.
Página 449 - Not being able to appreciate or conceive of the distinction between the psychical phenomena of a Chimpanzee and of a Boschisman or of an Aztec, with arrested brain growth, as being of a nature so essential as to preclude a comparison between them, or as being other than a difference of degree, I cannot shut my eyes to the significance of that all"pervading similitude of structure — every tooth, every bone, strictly homologous — which makes the determination of the difference between Homo and...
Página 29 - Not far from Shelbyville, in the State of Kentucky, about five years ago, there was one of these breeding places, which stretched through the woods in nearly a north and south direction ; was several miles in breadth, and was said to be upwards of forty miles in extent ! In this tract, almost every tree was furnished with nests, wherever the branches could accommodate them.
Página 30 - I was astonished at their appearance. They were flying with great steadiness and rapidity, at a height beyond gunshot, in several strata deep, and so close together, that could shot have reached them, one discharge could not have failed of bringing down several individuals. From right to left as far as the eye could reach, the breadth of this vast procession extended ; seeming everywhere equally crowded.
Página 17 - Paraguay, the parasitic insects would probably increase; and this would lessen the number of the navel-frequenting flies — then cattle and horses would become feral, and this would certainly greatly alter (as indeed I have observed in parts of South America) the vegetation: this again would largely affect the insects; and this, as we have just seen in Staffordshire, the insectivorous birds, and so onwards in ever-increasing circles of complexity.