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 53
... breed together , in order that the particular variations ( which from the point of view of the student of species - forming may be called also the particular varietal differences that are to become in time so developed and fixed as to ...
... breed together , in order that the particular variations ( which from the point of view of the student of species - forming may be called also the particular varietal differences that are to become in time so developed and fixed as to ...
Página 54
... breeding among themselves . But such an isolation may conceivably be brought about in several other ways , and observation has shown that probably in some cases so - called biologic isolation occurs , that is , that a restriction of ...
... breeding among themselves . But such an isolation may conceivably be brought about in several other ways , and observation has shown that probably in some cases so - called biologic isolation occurs , that is , that a restriction of ...
Página 58
... breeding with the mass . In a world of varying conditions with varying organisms , it is not conceivable that species should , through all their generations , undergo no change . Nor in the changes of any species is it possible that any ...
... breeding with the mass . In a world of varying conditions with varying organisms , it is not conceivable that species should , through all their generations , undergo no change . Nor in the changes of any species is it possible that any ...
Página 60
... breeding when thirty years old and goes on breeding until ninety years old , bringing forth six young in the interval and surviving to be a hundred years old . If this be so , after about 800 years there should be 19,000,000 elephants ...
... breeding when thirty years old and goes on breeding until ninety years old , bringing forth six young in the interval and surviving to be a hundred years old . If this be so , after about 800 years there should be 19,000,000 elephants ...
Página 66
... breeding at the age of six months , it is shown that , at this rate , the original pair might be responsible in five ... breed , and give himself and friends an occasional day with the hounds . His modest desires were soon met in the ...
... breeding at the age of six months , it is shown that , at this rate , the original pair might be responsible in five ... breed , and give himself and friends an occasional day with the hounds . His modest desires were soon met in the ...
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 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.