. The elements of experimental embryology. Embryology, Experimental; Embryology. Fig. 87 Spread of notochordal type of histo-differentiation to neighbouring organs in frog tadpoles reared in 1-5 per cent. urea. Left, notochordal differentiation in the gut-roof. Right, notochordal differentiation in the nerve cord. Below the noto- chord in each case is the sub-notochordal rod. (Redrawn after Jenkinson, Arch. Entiumech. xxi, 1906.) §8 We have left to the last what is the most celebrated example of de- pendent differentiation—the formation of the lens of the vertebrate eye from the epidermis unde
. The elements of experimental embryology. Embryology, Experimental; Embryology. Fig. 87 Spread of notochordal type of histo-differentiation to neighbouring organs in frog tadpoles reared in 1-5 per cent. urea. Left, notochordal differentiation in the gut-roof. Right, notochordal differentiation in the nerve cord. Below the noto- chord in each case is the sub-notochordal rod. (Redrawn after Jenkinson, Arch. Entiumech. xxi, 1906.) §8 We have left to the last what is the most celebrated example of de- pendent differentiation—the formation of the lens of the vertebrate eye from the epidermis under the influence of the eye-cup (fig. 86). The matter, however, is not simple, and is worth going into at some length. In Rana temporaria {fusca) the lens is dependent for its develop- ment on contact with the eye-cup. If the latter is removed (at the tail-bud stage), the lens is not formed.^ Further, the eye-cup in this species is capable of inducing the formation of a lens out of ^ Spemann, 1901A, 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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