The embryology and metamorphosis of the Macroura . layers of the ventralplate is still being increased by the migration of cells from the surface of this plate,as is indicated by cell ec, which is interpreted as a superficial cell about to migrate(in Fig. 98). In Fig. 100 a cell at the surface of the oi)tic disk is in the act of delami-uating. Large numbers of degenerating cells and their products are now encountered(,s.). REFERENCE LETTERS. A. (/), bud of tirst autenua. A. {II), bud of second antenna. Ab., Al. P., Ad. F., ventral plate. App., area of appendages. C. M., proliferatin
The embryology and metamorphosis of the Macroura . layers of the ventralplate is still being increased by the migration of cells from the surface of this plate,as is indicated by cell ec, which is interpreted as a superficial cell about to migrate(in Fig. 98). In Fig. 100 a cell at the surface of the oi)tic disk is in the act of delami-uating. Large numbers of degenerating cells and their products are now encountered(,s.). REFERENCE LETTERS. A. (/), bud of tirst autenua. A. {II), bud of second antenna. Ab., Al. P., Ad. F., ventral plate. App., area of appendages. C. M., proliferating area of optic disk. fc, ec., migrating and dividing cells at surface of ventral plate. Eel., Ep., ectoderm. .yd., rudiment of mandible. .Mes., mesoderm. 0. C, optic ganglion. 0. D., optic disk. «., s.^, products of degenerating chromatin. S. C, S. C.~-, cells in various stages of degeneration. St. A., sternal area. Std., stomodaium. T. C(i., Transverse sheet of ectoderm uniting optic disks. ¥., Y. S., yolk spheres. PUUe xxxriu Fig. 96 Fi^. F. H. Horrij-J<, lid . ALPHEUS 540 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. Plate XXXIX.(Stage VI.) Figs. 101-1j05. Serial longitudinal sections of early nauplius embryo, twelve and one-half hoursolder thai) that represented by Figs. 98-100, PI. xxxviii, and eighteen and oue-balfhours older than the stage represented in Fig. 93, PI. xxxvii. The thoracicoabdonii-nal fold or papilla is now forming, apparently by the ingrowth of the surface ectoblast(Fig. 104, Ab. C). Fig. 102 is exceptionally favorai)]e in showing the nn(lotil)teddelamination of two cells standing side by side at the surface of the optic disk (ec).The common radial division of the ectoderm of the thoracico-abdominal regionand other parts is illustrated by the cell ec of the same section. Fig. 105 cutsthe straight tubular stomodaeum. x 295. Fiti. 106. Longi tudinal median section of embryo several hours older than the last. A deep, narrow,transverse furrow {Ab. G.
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Keywords: ., bookauthor, bookcentury1800, bookdecade1890, booksubjectcrustacea
