. The development of the chick : an introduction to embryology. Embryology; Chickens -- Embryos. 82 THE DEVELOPMENT OF THE CHICK entoderm for a considerable period after the formation of the head- fold. A longitudinal section shows the head-process as an append- age to the anterior end of the primitive streak, or the primitive knot (Fig. 42).. Fig. 43. — Diagrams to illustrate the theory of concrescence as applied to the primitive streak of the bird. The central area bounded by the broken line represents the pellucid area; external to this is the area opaca, showing as concentric zones th
. The development of the chick : an introduction to embryology. Embryology; Chickens -- Embryos. 82 THE DEVELOPMENT OF THE CHICK entoderm for a considerable period after the formation of the head- fold. A longitudinal section shows the head-process as an append- age to the anterior end of the primitive streak, or the primitive knot (Fig. 42).. Fig. 43. — Diagrams to illustrate the theory of concrescence as applied to the primitive streak of the bird. The central area bounded by the broken line represents the pellucid area; external to this is the area opaca, showing as concentric zones the germ-wall (G. W.), the zone of junction (Z. J.), and the margin of overgrowth (M. O.). m. n., Marginal notch. For de- scription see text. The most obvious interpretation of the head-process is as an outgrowth from the primitive knot. But another, and more probable interpretation in view of all the facts, is that the head- process is a later stage of the anterior end of the primitive streak;. 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 Lillie, Frank Rattray, 1870-1947. New York : Henry Holt
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Keywords: ., bookauthorlilliefrankrat, bookcentury1900, booksubjectembryology
