Evolution and Animal Life: An Elementary Discussion of Facts, Processes, Laws and Theories Relating to the Life and Evolution of AnimalsD. Appleton, 1907 - 489 páginas |
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Página 57
... separation or isolation tends to preserve a special line of heredity from being merged in the mass which constitutes the parent stock or species . Without individual variation , no change could take place ; all organisms would be ...
... separation or isolation tends to preserve a special line of heredity from being merged in the mass which constitutes the parent stock or species . Without individual variation , no change could take place ; all organisms would be ...
Página 106
... separation of a few from the many by geographical or similar causes , by the perpetuation of the traits of these few ( the " survival of the existing " ) , all this being modified by the new range of natural and artificial selection and ...
... separation of a few from the many by geographical or similar causes , by the perpetuation of the traits of these few ( the " survival of the existing " ) , all this being modified by the new range of natural and artificial selection and ...
Página 109
... separation of individuals . Anything that could lead to exclusive or dis- criminate breeding among certain individuals of a species would result in the isolation of these individuals from the rest of the species as effectively as their ...
... separation of individuals . Anything that could lead to exclusive or dis- criminate breeding among certain individuals of a species would result in the isolation of these individuals from the rest of the species as effectively as their ...
Página 120
... separated . These groups of individuals are incipient species , and each may become in time an entirely distinct species if the barrier is really insurmountable . In the great water basin of the Mississippi , many families of fish occur ...
... separated . These groups of individuals are incipient species , and each may become in time an entirely distinct species if the barrier is really insurmountable . In the great water basin of the Mississippi , many families of fish occur ...
Página 122
... separated from the main flock , people an island , give their actual traits to their actual descendants , and the traits enforced by natural selection differ from island to island . If external conditions were alike in all the islands ...
... separated from the main flock , people an island , give their actual traits to their actual descendants , and the traits enforced by natural selection differ from island to island . If external conditions were alike in all the islands ...
Outras edições - Ver tudo
Evolution and animal life, an elementary discussion of facts, processes ... David Starr Jordan,Vernon Lyman Kellogg Visualização integral - 1908 |
Evolution and Animal Life: An Elementary Discussion of Facts, Processes ... David Starr Jordan,Vernon Lyman Kellogg Visualização integral - 1907 |
Evolution and animal life, an elementary discussion of facts, processes ... David Starr Jordan,Vernon Lyman Kellogg Visualização integral - 1907 |
Palavras e frases frequentes
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
Passagens conhecidas
Página 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.
Página 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.
Página 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.
Página 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.
Página 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.
Página 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.
Página 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.
Página 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.
Página 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.