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 51
... females have chosen for their consorts those males best endowed by variation with these ornamental character- istics , so that by this selection there has come about a gradual cumulation of the characteristics culminating in such ...
... females have chosen for their consorts those males best endowed by variation with these ornamental character- istics , so that by this selection there has come about a gradual cumulation of the characteristics culminating in such ...
Página 52
... female or hermaphroditic plant or animal produces , at least in the condition of eggs or germ cells , more than one new individual like itself . ( There are a very few exceptional cases , compensated for , however , in other ways ...
... female or hermaphroditic plant or animal produces , at least in the condition of eggs or germ cells , more than one new individual like itself . ( There are a very few exceptional cases , compensated for , however , in other ways ...
Página 59
... female quinnat salmon of the Columbia , Oncorhynchus tchawytscha , ascends the river at the age of about four years , and lays 4,000 eggs , after which she dies . Half these eggs develop into males . If each female egg came to maturity ...
... female quinnat salmon of the Columbia , Oncorhynchus tchawytscha , ascends the river at the age of about four years , and lays 4,000 eggs , after which she dies . Half these eggs develop into males . If each female egg came to maturity ...
Página 71
... female individuals of the same species are the rule rather than the exception ( Fig . 40 ) . Many of these differences are what might be called the necessary ones due to the particular functions assumed by each individual in this ...
... female individuals of the same species are the rule rather than the exception ( Fig . 40 ) . Many of these differences are what might be called the necessary ones due to the particular functions assumed by each individual in this ...
Página 72
... female mammals , the brood pouches of the female kangaroos and opossums , etc. But a moment's reflection calls to mind the existence of a host of other differ- ences between males and females of the same species which plainly have no ...
... female mammals , the brood pouches of the female kangaroos and opossums , etc. But a moment's reflection calls to mind the existence of a host of other differ- ences between males and females of the same species which plainly have no ...
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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 animals and plants ants apes appear artificial selection bees beetles biologists birds body breeding butterfly called causes centrosome changes CHAPTER characters chromatin chromosomes color and pattern common crab Darwin degeneration degree descent differentiation division egg cell embryo environment existence fact factors fauna female fertilized fishes forms fossils gastrula genus germ cells habit hatched heredity host hybrid individuals influence inheritance insects instinct islands isolation kinds of animals known larva larvæ live lower male mammals matter ment modified mutations natural selection naturalists nest nucleus offspring organic evolution origin Origin of Species parasites parent phenomena plasm primitive produced protoplasm Protozoa race relation reproduction reptiles resemblance Sacculina sea anemone sexual sexual selection sheep species species-forming sperm spines stage structure substance tail theory tion traits tree variation various vertebrates Weismann wings workers young
Passagens conhecidas
Página 468 - 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 426 - ... 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. To do this effectually it is necessary to be fully possessed of 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 426 - 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 137 - 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 differs, more or less, from the same part in the parents.
Página 468 - 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 120 - 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.
Página 63 - 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." Hence it is quite credible that the presence of a feline animal in large numbers in a district might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district!
Página 311 - There are twenty-six land birds. Of these twenty-one, or perhaps twenty-three, are ranked as distinct species, and would commonly be assumed to have been here created; yet the close affinity of most of these birds to American species is manifest in every character in their habits, gestures and tones of voice.
Página 63 - Newman, who has long attended to the habits of humble-bees, believes that "more than two-thirds of them are thus destroyed all over England.