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adult female adult male apical apical mark appear band bird black bars black crescent blackish breast brown buff chequers color color-patterns common pigeon crested pigeon cuneata dark center direction distal domestic pigeons European turtle-dove evolution Explanation of Plate figure frills fundamental bars Geopelia cuneata Geopelia humeralis gray guinea-mark hatched Hayashi homer hybrid iridescence juvenal feathers later left wing lesser coverts light edge livia long coverts lower margin median middle mourning-dove mutation narrow natural selection neck neck-mark ontogeny oriental turtle-dove origin origin of species orthogenetic outer pangenesis passerina Peristera Phaps chalcoptera pigment plumage posterior primaries reduced ring-dove rock-pigeon row of coverts rufous Salvadori scapulars secondaries seen Selected feathers side species spots stages streak subterminal tail-coverts Temminck tertials text-fig Text-figure transverse bars turtle-dove pattern Turtur unit-characters upper variation vinous Vries width Wing of adult Wing of juvenal wing-bars wing-coverts young Zenaida Zenaidura
Page 35 - ... and as modern geology has almost banished such views as the excavation of a great valley by a single diluvial wave, so will natural selection, if it be a true principle, banish the belief of the continued creation of new organic beings, or of any great and sudden modification in their structure.
Page 9 - Species have not arisen through gradual selection, continued for hundreds or thousands of years, but by jumps (stufenweise) through sudden, though small, transformations. In contrast with variations which are changes advancing in a linear direction, the transformations to be called mutations diverge in new directions. They take place, then, so far as experience goes, without definite direction.
Page 174 - ... he will not be able to assign a shadow of an explanation. He will be forced to admit that these great and sudden transformations have left no trace of their action on the embryo. To admit all this is, as it seems to me, to enter into the realms of miracle, and to leave those of Science.
Page 119 - London, 1886. alternate dark or light bands or spots, such as the zebra, some deer, or the carnivora, we find, first, that the region of the spinal column is marked by a dark stripe ; secondly, that the regions of the appendages, or limbs, are differently marked ; thirdly, that the flanks are striped or spotted, along or between the regions of the lines of the ribs ; fourthly, that the shoulder and hip regions are marked by curved lines ; fifthly, that the pattern changes, and the direction of the...
Page 64 - But the causes and conditions of variation have yet to be thoroughly explored; and the importance of natural selection will not be impaired, even if further inquiries should prove that variability is definite and is determined in certain directions rather than in others, by conditions inherent in that which varies.
Page 11 - I venture to assert thai variation is sometimes orderly, and at other times rather disorderly, and that the one is just as free from teleology as the other. In our aversion to the old teleology so effectually banished from science by Darwin we should not forget that the world is full of order, the inorganic no less than the organic. Indeed, what is the whole development of an organism if not strictly and marvellously orderly?
Page 46 - ... I would only add, that the slowness and the rapidity of the intestinal movements are proportionate, in the different species of animals, to the necessity for alimentation which varies with the species. I would also recall to your recollection that, in a normal state, these movements are performed more rapidly in the upper than in the lower part of the intestines — that they are more rapid in the ileum than in the large intestine — in the jejunum than in the ileum — in the duodenum than...
Page 9 - ... coupled with an equally intemperate advocacy of the notion that organic evolution depends upon the inheritance of acquired characters, was enough to prejudice the whole case of orthogenesis. Moreover, the controversial setting given to the idea of definitely directed variation, without the aid of utility and natural selection, made it difficult to escape the conclusion that orthogenesis was only a new form of the old teleology, from the paralyzing domination of which Darwin and Lyell and their...