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acquired characters adaptation adult albino animals and plants appear become birds blood body breeding causes changes chapter Charles Darwin chromatin chromomeres color correlation cross-over percentage crossed Darwin descendants determiner division dominant Drosophila dwarf effect embryology energy environment Eocene eugenics euthenic evidence existence explain fact factors female fertilization forms fossils gametes genera genes genetics germ cells germ plasm germ-cells germinal hereditary heredity human hybrids hypothesis inbred individuals inheritance island isolation kind Lamarck lamarckiana later less linkage living lower male mammals Mendel's Mendelian Mendelian inheritance modification mutations natural selection normal number of chromosomes observed occur offspring organic evolution origin Origin of Species orthogenesis ovum parent peculiar present produced pure race ratio recessive reduction division resemblance result scutes seeds sexual shown somatic species stage structure tall teeth tion tissues variations varieties vestigial structures Vries young zygote
Page 236 - As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever-branching and beautiful ramifications.
Page 4 - It is interesting to contemplate an entangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us.
Page 223 - In these several senses, which pass into each other, I use for convenience' sake the general term of Struggle for Existence.
Page 251 - Several writers have misapprehended or objected to the term Natural Selection. Some have even imagined that natural selection induces variability, whereas it implies only the preservation of such variations as arise and are beneficial to the being under its conditions of life.
Page 271 - 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.
Page 227 - Nature's productions should be far 'truer' in character than man's productions; that they should be infinitely better adapted to the most complex conditions of life, and should plainly bear the stamp of far higher workmanship?
Page 4 - These laws, taken in the largest sense, being Growth with reproduction; Inheritance which is almost implied by reproduction; Variability from the indirect and direct action of the conditions of life, and from use and disuse: a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing Divergence of Character and the Extinction of less improved forms.
Page 225 - ... seriously disturb the relations of some of the former inhabitants. Let it be remembered how powerful the influence of a single introduced tree or mammal has been shown to be. But in the case of an island, or of a country partly surrounded by barriers, into which new and better adapted forms could not freely enter, we should then have places in the economy of nature which would assuredly be better filled up, if some of the original inhabitants were in some manner modified ; for, had the area been...
Page 4 - There is a 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.
Page 29 - ... success in his own sphere of activity, plunges into scientific questions with which he has no real acquaintance, only to obscure them by an aimless rhetoric, and distract the attention of his hearers from the real point at issue by eloquent digressions and skilled appeals to religious prejudice.