. Text-book of embryology. Embryology. 172 INVEETEBEATA CHAP. Till to a prae-oral position; the other appendages develop in order from before backwards. Into each rudimentary appendage an outgrowth of the corresponding somite with its coelomic cavity extends. Then the endodermic tube shrinks away from the ectoderm and leaves. "Fig. 124. — Stages in the division of the blastopore and the formation of the mesoderm of Peripatus capensis. (After Sedgwick.) A, the blastopore elongated but imconstricted ; the primitive streak is seen behind the blastopore. B, the blastopore has just divided int
. Text-book of embryology. Embryology. 172 INVEETEBEATA CHAP. Till to a prae-oral position; the other appendages develop in order from before backwards. Into each rudimentary appendage an outgrowth of the corresponding somite with its coelomic cavity extends. Then the endodermic tube shrinks away from the ectoderm and leaves. "Fig. 124. — Stages in the division of the blastopore and the formation of the mesoderm of Peripatus capensis. (After Sedgwick.) A, the blastopore elongated but imconstricted ; the primitive streak is seen behind the blastopore. B, the blastopore has just divided into mouth in front and anus behind. The mesodermic' bands have been formed and have already budded off somites in front. C, the embryo has become concave ventrally. The appendages are beginning to grow out from the somites, a, anus ; ap, appendage; at, rudiment of antenna ; blp, blastopore; m, mouth; , primitive streak; som, somites. spaces which eventually form the body-cavity of the adult, a cavity which is totally distinct from the coelom and is termed the haemo- coele since it becomes filled with blood (Gr. haema, blood). It corre- sponds exactly to the blastocoele or primary body-cavity of the Annelid larva. Of these spaces three primary ones may be dis- tinguished, namely, one median ventral and two dorso-lateral ( 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 MacBride, E. W. (Ernest William), 1866-1940; Kerr, John Graham, 1869-; Heape, Walter, 1855-1929. London : Macmillan
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