. The elements of experimental embryology. Embryology, Experimental; Embryology. Fig. 40 One embryo from two eggs. Left, two Triton eggs in the 2-cell stage are laid across each other, so that their blastomeres alternate. Centre, each blastomere has divided once. Right, a giant neurula resulting from such a fusion. (After Seidel, from Morgan, Experimental Embryology, Columbia University Press, 1927, modified.) restricted to injuring one of the blastomeres: this is usually accom- plished with a hot needle. The result of such an experiment at the 2-cell stage is that the uninjured blastomere dev
. The elements of experimental embryology. Embryology, Experimental; Embryology. Fig. 40 One embryo from two eggs. Left, two Triton eggs in the 2-cell stage are laid across each other, so that their blastomeres alternate. Centre, each blastomere has divided once. Right, a giant neurula resulting from such a fusion. (After Seidel, from Morgan, Experimental Embryology, Columbia University Press, 1927, modified.) restricted to injuring one of the blastomeres: this is usually accom- plished with a hot needle. The result of such an experiment at the 2-cell stage is that the uninjured blastomere develops into a half- embryo, and does not produce much more than it would have done if its sister-blastomere had developed normally alongside it, for it is a condition of the experiment that the injured blastomere re- mains attached to the uninjured one.^ (For the present purpose, the subsequent attempt of the half-embryo to complete itself by " post-generation "'-^ may be passed over here as irrelevant (fig. 41).) 1 Roux, 1888. ^ In some of the cases originally described by Roux, the half-embryo obtained by injuring one blastomere with a hot needhe appeared to be subsequently con- verted into a whole embryo, by the utilisation of the materials of the injured blastomere. To this restorative process, the name "post-generation" was given. It was imagined that the reorganisation of the injured blastomere was brought about either by belated cleavage of its nucleus, or by invasion of cells from the uninjured half, or by overgrowth of the injured half by layers of tissue from 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 Huxley, Julian, 1887-1975; De Beer, Gavin, Sir, 1899-1972. New York [Hafner Pub. Co. ]
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