. The elements of experimental embryology. Embryology, Experimental; Embryology. i88 organisers: inducers of differentiation to induction. There is thus an overlap in time between these two phases of differentiation ordinarily spoken of as dependent differ- entiation and self-differentiation. There seems to be little reason to doubt, however, that both the methods concerned in '* double assurance " are ultimately referable to one and the same causative agent: in this case presumably situated in the rudiment of the eye-cup and in the fully formed cup which later arises from Fig. 90 Le
. The elements of experimental embryology. Embryology, Experimental; Embryology. i88 organisers: inducers of differentiation to induction. There is thus an overlap in time between these two phases of differentiation ordinarily spoken of as dependent differ- entiation and self-differentiation. There seems to be little reason to doubt, however, that both the methods concerned in '* double assurance " are ultimately referable to one and the same causative agent: in this case presumably situated in the rudiment of the eye-cup and in the fully formed cup which later arises from Fig. 90 Lens-formation from the margin of the optic cup in ontogenetic development. The presumptive eye-rudiment of an embryo of Triton was grafted into the side of the body of another embryo, and developed by self-differentiation, deep beneath the epidermis. Under these circumstances it has given rise to a lens from the margin of its own cup, in themanner characteristic of regeneration experi- ments. Br. portion of grafted brain tissue; wall of intestine; L. lens; S. epi- dermis of ventral side. (From Adelmann, Arch. Entwmech. cxiii, 1928.) The divergent results obtained with different species are ap- parently to be accounted for by differences in the rates at which the two processes, of capacity of the eye-cup to induce and of the epidermis to differentiate, occur. The proliferation of cells from the epidermis is not, however, the only process involved in lens-formation: the cells require to become converted into the characteristic lens-fibres. While 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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