. Darwin, and after Darwin. An exposition of the Darwinian theory and a discussion of post-Darwinian questions. Evolution; Heredity. Fig. 71.âTail ol ArchcBOpteryx. A indicates origin of simply- jointed tail. â â â .!;:â ^iiJ-'^'u^^'i^^ Fig. 72.âTail of modem Bird. The numerals indicate the fore- shortened, enlarged, and con- solidated joints; f, terminal segment of the vertebral column; D, shafts of feathers. Now, in the development of a teleost fish (Fig. 68), as has been shown by Alexander Agassiz, the tail-fin is first like Fig. 70; then becomes heterocercal, like Fig. 69 ; and, finally, b
. Darwin, and after Darwin. An exposition of the Darwinian theory and a discussion of post-Darwinian questions. Evolution; Heredity. Fig. 71.âTail ol ArchcBOpteryx. A indicates origin of simply- jointed tail. â â â .!;:â ^iiJ-'^'u^^'i^^ Fig. 72.âTail of modem Bird. The numerals indicate the fore- shortened, enlarged, and con- solidated joints; f, terminal segment of the vertebral column; D, shafts of feathers. Now, in the development of a teleost fish (Fig. 68), as has been shown by Alexander Agassiz, the tail-fin is first like Fig. 70; then becomes heterocercal, like Fig. 69 ; and, finally, be- comes homocercal like Fig. 68. Why so.'' Not because there is any special advantage in this succession of forms; for the changes take place either in the 'g or else in very early em- bryonic states. The answer is found in the fact that this is the order of change in the phylogenetic series. The earliest fish-tails were either like Fig. 69 or Fig. 70; never like Fig. 68. The. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Romanes, George John, 1848-1894. Chicago The Open Court Pub. Co
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