Contributions to the Theory of Natural Selection |
From inside the book
Page 271
There is a Madagascar Orchis—the Angraecum sesquipedale—with an
immensely long and deep nectary. How did such an extraordinary organ come to
be developed ? Mr. Darwin's explanation is this. The pollen of this flower can only
be ...
There is a Madagascar Orchis—the Angraecum sesquipedale—with an
immensely long and deep nectary. How did such an extraordinary organ come to
be developed ? Mr. Darwin's explanation is this. The pollen of this flower can only
be ...
Page 272
In our British species, such as Orchis pyramidalis, it is not necessary that there
should be any exact adjustment between the length of the nectary and that of the
proboscis of the insect; and thus a number of insects of various sizes are found to
...
In our British species, such as Orchis pyramidalis, it is not necessary that there
should be any exact adjustment between the length of the nectary and that of the
proboscis of the insect; and thus a number of insects of various sizes are found to
...
Page 273
... our cultivated fruits and flowers. But this would lead in time to such an
increased length of the nectary that many of the moths could only just reach the
surface of the nectar, and only the few with exceptionally long trunks be able to
suck up a ...
... our cultivated fruits and flowers. But this would lead in time to such an
increased length of the nectary that many of the moths could only just reach the
surface of the nectar, and only the few with exceptionally long trunks be able to
suck up a ...
Page 274
If, for instance, the variation in the quantity of nectar had been at any stage
greater than the variation in the length of the nectary, then smaller moths could
have reached it and have effected the fertilization. Or if the growth of the
probosces of ...
If, for instance, the variation in the quantity of nectar had been at any stage
greater than the variation in the length of the nectary, then smaller moths could
have reached it and have effected the fertilization. Or if the growth of the
probosces of ...
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action adapted allied animals appear beauty become believe birds body build butterflies causes changes character closely colour common comparatively complete consider conspicuous continually direction distinct doubt earth effect equally evidence exactly example existence explain extinct facts female flowers forces further genera genus geological give given greater groups habits imitation important increase individuals inhabiting insects instinct islands kind known less limited living male materials matter means mimicry mind mode modifications moths natural selection necessary nest never objects observations occur organic origin Papilio perfect period phenomena possess present probably produced protection prove race reason regions remarkable render resemble result savage seems sexes shown similar species structure supposed theory tints tion trees true universe variation varied varieties various whole wings young
Popular passages
Page 368 - If, therefore, we have traced one force, however minute, to an origin in our own WILL, while we have no knowledge of any other primary cause of force, it does not seem an improbable conclusion that all force may be will-force ; and thus, that the whole universe, is not \ merely dependent on, but actually is, the WILL of higher intelligences or of one Supreme Intelligence.
Page 25 - Every species has come into existence coincident both in time and space with a preexisting closely allied species," Connects together and renders intelligible a vast number of independent and hitherto unexplained facts.
Page 35 - Even a change of colour might, by rendering them more or less distinguishable, affect their safety; a greater or less development of hair might modify their habits. More important changes, such as an increase in the power or dimensions of the limbs or any of the external organs, would more or less affect their mode of procuring food or the range of country which they inhabit.
Page 286 - Strictly speaking, therefore, Mr. Darwin's theory is not a theory on the Origin of Species at all, but only a theory on the causes which lead to the relative success or failure of such new forms as may be born into the world.
Page 38 - ... applied to high numbers, the results come nearer to what theory demands, and, as we approach to an infinity of examples, become strictly accurate. Now the scale on which nature works is so vast — the numbers of individuals and periods of time with which she deals approach so near to infinity, that any cause, however slight, and however liable to be veiled and counteracted by accidental circumstances, must in the end produce its full legitimate results.
Page 359 - A superior intelligence has guided the development of man in a definite direction and for a special purpose, just as man guides the development of many animal and vegetable forms...
Page 26 - One of the strongest arguments which have been adduced to prove the original and permanent distinctness of species is, that varieties produced in a state of domesticity are more or less unstable, and often have a tendency, if left to themselves, to return to the normal form of the parent species; and this instability is considered to be a distinctive peculiarity of all varieties, even of those occurring among wild animals in a state of nature, and to constitute a provision for preserving unchanged...
Page 356 - Natural Selection could only have endowed the savage with a brain a little superior to that of an ape, whereas he actually possesses one but very little inferior to that of the average members of our learned societies.
Page 30 - ... annually, — a striking result, but one which seems at least highly probable, and is perhaps under rather than over the truth. It would therefore appear that, as far as the continuance of the species and the keeping up the average number of individuals are concerned, large broods are superfluous. On the average all above one become food for hawks and kites, wild cats and weasels, or perish of cold and hunger as winter comes on.
Page 368 - God of the Granite and the Rose ! Soul of the Sparrow and the Bee ! The mighty tide of Being flows Through countless channels, Lord, from Thee. It leaps to life in grass and flowers, Through every grade of being runs, While from Creation's radiant towers Its glory flames in Stars and Suns.
Bibliographic information
| Title | Contributions to the Theory of Natural Selection |
| Author | Alfred Russel Wallace |
| Published | 1871 |
| Original from | the University of Michigan |
| Digitized | 17 veeb. 2006 |
| Export Citation | BiBTeX EndNote RefMan |