. The elements of experimental embryology. Embryology, Experimental; Embryology. ORIGIN OF POLARITY, SYMMETRY, AND ASYMMETRY 71 It is clear that a fandamental difference must exist between the eggs of bilaterally symmetrical and those of radially symmetrical forms. In the former case, however, what is given by genetic con- stitution cannot be bilateral symmetry per se, but the capacitv of developing such symmetry in relation to various external agencies. Harrison (1921 A, 1925 a) has suggested that the ultimate capacity for developing symmetry-relations is linked up with the intimate propertie
. The elements of experimental embryology. Embryology, Experimental; Embryology. ORIGIN OF POLARITY, SYMMETRY, AND ASYMMETRY 71 It is clear that a fandamental difference must exist between the eggs of bilaterally symmetrical and those of radially symmetrical forms. In the former case, however, what is given by genetic con- stitution cannot be bilateral symmetry per se, but the capacitv of developing such symmetry in relation to various external agencies. Harrison (1921 A, 1925 a) has suggested that the ultimate capacity for developing symmetry-relations is linked up with the intimate properties of the protoplasm and the "space-lattice " formed by its constituent parts. The asymmetry of the large chelae found in many Crustacea either in one or both sexes, and also that of the opercula in certain. 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 Huxley, Julian, 1887-1975; De Beer, Gavin, Sir, 1899-1972. New York [Hafner Pub. Co. ]
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