. The development of the chick; an introduction to embryology. Birds -- Embryology. DEVELOPMENT PRIOR TO LAYING 55 The margin of invasination is known as the hp of the blasto- ] pore or primitive mouth; the space between this margin and the volk is the blastopore, and the space between the entodem -^ and yolk, derived from part of the subgerminal cavity, is tlie^ archenteron or primitive Fig. 27. â Diagrammatic reconstruction of the blasto- derm of which a longitudinal section is shown in Fig. 26. Plane of Fig. 26. â - â i- , G. W., Germ-wall 1, 2, 3, 4, 5, 6, and ' >â¢lio
. The development of the chick; an introduction to embryology. Birds -- Embryology. DEVELOPMENT PRIOR TO LAYING 55 The margin of invasination is known as the hp of the blasto- ] pore or primitive mouth; the space between this margin and the volk is the blastopore, and the space between the entodem -^ and yolk, derived from part of the subgerminal cavity, is tlie^ archenteron or primitive Fig. 27. â Diagrammatic reconstruction of the blasto- derm of which a longitudinal section is shown in Fig. 26. Plane of Fig. 26. â - â i- , G. W., Germ-wall 1, 2, 3, 4, 5, 6, and ' >â¢lioate regions of the blastoderm which are approximately from 1 to 7 cells deep respectively. The broken line around 1 indicates the region where the blastoderm is approxi- mLtely one cell d?ep. x (After Patterson.) The first stage in the formation of the entoderm is interpreted as involution of the free margin, and this view is supported by the fact, determined by Patterson, that the diameter of the blastoderm is shorter than the transverse diameter during this process, whereas previously the blastoderm was approximately circular. An even stronger support of this view is furnished bv experiments which demonstrate that injuries to the margin made just prior to gastrulation appear later in an. 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, Holt
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Keywords: ., bookauthorlilliefrankrattray187, bookcentury1900, bookdecade1900
