Darwinism To-day: A Discussion of Present-day Scientific Criticism of the Darwinian Selection Theories, Together with a Brief Account of the Principal Other Proposed Auxiliary and Alternative Theories of Species-forming |
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acquired characters acters actual adaptation advantage animals appear artificial selection basis believe biological biologists biophors birds breeding capacity cells characteristics colour complex congenital variations correlation crabs criticism Darwin Darwin'schen Darwinian Darwinian variations Darwinismus definite Delage determinants direct effects Eimer environment example explain fact factor favourable female fluctuating variations follows functional gemmules germ-cells germ-plasm germinal selection groups heredity heterogenesis individuals Individuen influence inheritance of acquired insects isolation kind können Lamarckian Lamarckism larvæ less males ment modification mutations theory natural selection natural selection theory neo-Darwinism objection observed occur offspring ontogenetic origin of species orthogenesis pangenes panmixia parents Parus rufescens phenomena physiological plants Plate principle produced protoplasm race recognised result says Science secondary sexual characters Selektion sexual selection slight specialisation species-forming stimuli structure struggle for existence survival teleology theory of descent theory of species-forming variability variety varying Vries Vries's Weismann Wolff
Popular passages
Page 239 - 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 34 - ... being similarly acted on — of which fact numerous instances could be given with our domestic productions. In such cases, if the varying individual did not actually transmit to its offspring its...
Page 73 - First, why, if species have descended from other species by fine gradations, do we not everywhere see innumerable transitional forms? Why is not all nature in confusion, instead of the species being, as we see them, well defined?
Page 98 - The more bountifully the parent is gifted by nature, the more rare will be his good fortune if he begets a son who is as richly endowed as himself, and still more so if he has a son who is endowed yet more largely.
Page 5 - The fair truth is that the Darwinian selection theories, considered with regard to their claimed capacity to be an independently sufficient mechanical explanation of descent, stand to-day seriously discredited in the biological world. On the other hand, it is also fair truth to say that no replacing hypothesis or theory of species-forming has been offered by the opponents of selection which has met with any general or even considerable acceptance by naturalists.
Page 34 - There can also be little doubt that the tendency to vary in the same manner has often been so strong that all the individuals of the same species have been similarly modified without the aid of any form of selection. Or only a third, fifth, or tenth part of the individuals may have been thus affected, of which fact several instances could be given.
Page 55 - This is a tremendous fact, upsetting all the calculations of physicists as to the duration in past and future of the sun's heat and the temperature of the earth's surface. The geologists and the biologists have long contended that some thousand million years must have passed during which the earth's surface has presented approximately the same conditions of temperature as at present, in order to allow time for the evolution of living things and the formation of the aqueous deposits of the earth's...
Page 291 - ... 4th. Partial closure of the eyelids in animals born of parents in which that state of the eyelids had been caused either by the section of the cervical sympathetic nerve or the removal of the superior cervical ganglion. " ' 5th. Exophthalmia in animals born of parents in which an injury to the restiform body had produced that protrusion of the eyeball.
Page 229 - Weismann has piled up one hypothesis on another as though he could save the integrity of the theory of natural selection by adding new speculative matter to it. The most unfortunate feature is that the new speculation is skilfully removed from the field of verification, and invisible germs, whose sole functions are those which Weismann's imagination bestows on them, are brought forward as though they could supply the deficiencies of Darwin's theory. This is, indeed, the old method of the philosophises...
Page 34 - Or only a third, fifth, or tenth part of the individuals may have been thus affected, of which fact several instances could be given. Thus Graba estimates that about onefifth of the guillemots in the Faroe Islands consist of a variety so well marked, that it was formerly ranked as a distinct species under the name of Uria lacrymans.