. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. 198 THE ASCJDIANS. Formation of Medullary Tube and Notochord. Here, as in Amphioxus, the dorsal wall of the embryo flattens, while the ventral remains convex, and the ecto- dermic cells on the dorsal side become marked off from the rest by their larger size and columnar shape. The medullary plate extends nearly to the front end of the embryo, while posteriorly its cells form a ring round the blastopore. In the formation of the medullary tube, however, there is an important difference, and the Ascidian embryo
. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. 198 THE ASCJDIANS. Formation of Medullary Tube and Notochord. Here, as in Amphioxus, the dorsal wall of the embryo flattens, while the ventral remains convex, and the ecto- dermic cells on the dorsal side become marked off from the rest by their larger size and columnar shape. The medullary plate extends nearly to the front end of the embryo, while posteriorly its cells form a ring round the blastopore. In the formation of the medullary tube, however, there is an important difference, and the Ascidian embryo con- forms in this point more to the mode of development â mJ. 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 Willey, Arthur, 1867-. New York, London, Macmillan
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1894
