Evolution and Animal Life: An Elementary Discussion of Facts, Processes, Laws and Theories Relating to the Life and Evolution of AnimalsD. Appleton, 1907 - Всего страниц: 489 |
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Стр. 83
... sheep or its owner . They are nonadaptive or FIG . 48. - Typical Dorset ewe , horned . ( After Shaw . ) FIG . 49. - Polled Welsh sheep , a primitive type , lean and scant wooled . ( After Youatt . ) indifferent characters . These ...
... sheep or its owner . They are nonadaptive or FIG . 48. - Typical Dorset ewe , horned . ( After Shaw . ) FIG . 49. - Polled Welsh sheep , a primitive type , lean and scant wooled . ( After Youatt . ) indifferent characters . These ...
Стр. 84
... sheep . While in race traits , the breeds ( uncrossed ) tend to diverge from one another , in these adaptive ... sheep he may like , and then in time reproduce it through selective breeding . In Nova Scotia , Mr. A. Graham Bell has ...
... sheep . While in race traits , the breeds ( uncrossed ) tend to diverge from one another , in these adaptive ... sheep he may like , and then in time reproduce it through selective breeding . In Nova Scotia , Mr. A. Graham Bell has ...
Стр. 87
... 7 5 3 1 high degree . The Southdown sheep are valued - not. FIG . 53. Various races of pigeons , all probably descended from the European rock dove , Columba livia . ( After Haeckel . ) FIG . 55. - Wild boar contrasted with modern domestic.
... 7 5 3 1 high degree . The Southdown sheep are valued - not. FIG . 53. Various races of pigeons , all probably descended from the European rock dove , Columba livia . ( After Haeckel . ) FIG . 55. - Wild boar contrasted with modern domestic.
Стр. 88
... sheep are valued - not for their Southdown traits , but for the excellence of their mutton , a trait with which middle length of wool , tawny legs , naked faces , drooping ears , and absence of horns have nothing necessarily to do . We ...
... sheep are valued - not for their Southdown traits , but for the excellence of their mutton , a trait with which middle length of wool , tawny legs , naked faces , drooping ears , and absence of horns have nothing necessarily to do . We ...
Стр. 104
... sheep have black ears , but by persistent se- lection the ears could probably be made white . Probably also the horns of the Dorsets could be bred on Hampshires by making use of possible occasional reversions to the horned stock . This ...
... sheep have black ears , but by persistent se- lection the ears could probably be made white . Probably also the horns of the Dorsets could be bred on Hampshires by making use of possible occasional reversions to the horned stock . This ...
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actual adaptation adult animals and plants ants appear artificial selection become bees beetles biologists birds body breeding Burbank butterfly called causes centrosome changes characters chromatin chromosomes color and pattern common crab Darwin degeneration degree division egg cell embryo environment evolution existence fact factors fauna feeding female fertilized fishes forms fossils gastrula genus germ cells habit hatched heredity honeybee host hybrid individuals influence inheritance insects instinct islands isolation kinds of animals larva larvæ legs live lower male mammals ment modified mutations natural selection naturalists nest nucleus offspring organs Origin of Species original parasites parent phenomena plasm produced protoplasm Protozoa rabbit race relation reproduction resemblance rocks Sacculina sea anemone sexual sexual selection sheep simple species species-forming sperm spines stage structure tail tetrads theory tion traits tree variation various vertebrates Vries Weismann wings workers worm young
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Стр. 466 - There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.
Стр. 424 - ... duty of each and all of us is to try to make the little corner he can influence somewhat less miserable and somewhat less ignorant than it was before he entered it. To do this effectually it is necessary to be fully possessed of only two beliefs: the first, that the order of nature is ascertainable by our faculties to an extent which is practically unlimited; the second, that our volition counts for something as a condition of the course of events.
Стр. 23 - ... x's and y's with which he works his problems, for real entities — and with this further disadvantage, as compared with the mathematician, that the blunders of the latter are of no practical consequence, while the errors of systematic materialism may paralyse the energies and destroy the beauty of a life.
Стр. 466 - To my mind it accords better with what we know of the laws impressed on matter by the Creator, that the production and extinction of the past and present inhabitants of the world should have been due to secondary causes, like those determining the birth and death of the individual.
Стр. 424 - We live in a world which is full of misery and ignorance, and the plain duty of each and all of us is to try to make the little corner he can influence somewhat less miserable and somewhat less ignorant than it was before he entered it.
Стр. 61 - Near villages and small towns I have found the nests of humble-bees more numerous than elsewhere, which I attribute to the number of cats that destroy the mice.
Стр. 135 - Our ignorance of the laws of variation is profound. Not in one case out of a hundred can we pretend to assign any reason why this or that part has varied.
Стр. 455 - Thus, whatever system of organs be studied, the comparison of their modifications in the ape series leads to one and the same result — that the structural differences which separate man from the gorilla and the chimpanzee are not so great as those which separate the gorilla from the lower apes.
Стр. 118 - Given any species in any region, the nearest related species is not likely to be found in the same region, nor in a remote region, but in a neighboring district, separated from the first by a barrier of some sort, or at least by a belt of country the breadth of which gives the effect of a barrier.