File:The Journal of experimental zoology (1905) (14593523938).jpg

Identifier: journalofexperim02harr (find matches)
Title: The Journal of experimental zoology
Year: 1905 (1900s)
Authors: Harrison, Ross G. (Ross Granville), 1870-1959 Brooks, William Keith, 1848-1908 Wistar Institute of Anatomy and Biology American Society of Zoologists
Subjects: Zoology
Publisher: (New York, etc.) Wiley-Liss (etc.)
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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Text Appearing Before Image:
ots are present. Fig. 35. Left-anterior three-quarter embryo, dorsal view; the right posterior quadrant (B^) waskilled in the 4-cell stage and the embryo fixed 6 hours later. The anterior half of the embryo is entirelynormal. The muscle cells are lacking on the right side though they have begun to grow around thehinder end of the notochord. The posterior portion of the trunk mesenchyme is found only on the leftside, but its anterior portion, which is derived from the cells A-^ and A^* (Fig. 6) of the anterior quad-rants is present on both sides. In the region of the injured cell the notochord and neural tube arecurved away from that cell. Fig. 36. Left half embryo, from left side; spurted in the 4-cell stage, fixed 6 hours later. Thedorsal lip of the blastopore is being overgrown by the ventral (posterior) lip. Muscle cells andmesenchyme are found only on the left side. The neural plate is abnormally folded, but still open;sense spots are present. Mosaic Developynent in Ascidian Eggs.
Text Appearing After Image:
168 Edivm G. Conklin. c. Formation of Larva. A considerably later stage in the development of the half embryois shown in Figs. 32, 33 and 36 (Figs. 34 and 35 are three-quarterembryos and will be described later); of these stages Fig. 33 is theyoungest and Fig. 36 the oldest. In all ot these figures the blasto-pore has already closed and the chorda cells have given rise to afusiform notochord, which lies in the posterior half of the embryo.The blastopore closes chiefly by the posterior growth of the dorsal(anterior) lip, as in the normal gastrula. With the formation ofthe notochord the posterior half of the embryo becomes elongatedand narrower than the anterior half and the developing tail bendsaround toward the injured side. (Figs. 32, 33.) The anterior half remains large, the posterior half becomes longand narrow; the latter portion contains the notochord and musclecells, the former the gastral endoderm, mesenchyme and most ofthe neural plate. The general superficial appearance of an

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