. The Biological bulletin. Biology; Zoology; Marine biology. «;%; .3* i& * a. * k* *. * »• •.*. * Fig. 9. Transverse section through the center of the blastoderm of a pigeon's eggtakenat 10:30 A. M., 14^2 hours after fertilization. 1. Marginal cell. 2. Mar- ginal periblast. 3. Nuclei in the central periblast, derived from the nucleus of the marginal cell. protrusions from the central periblast extend into the segmenta- tion cavity. Nuclei are often found in these protrusions, which suggest that cells are being added to the segmented part. This egg is still in the cleavage stage, being
. The Biological bulletin. Biology; Zoology; Marine biology. «;%; .3* i& * a. * k* *. * »• •.*. * Fig. 9. Transverse section through the center of the blastoderm of a pigeon's eggtakenat 10:30 A. M., 14^2 hours after fertilization. 1. Marginal cell. 2. Mar- ginal periblast. 3. Nuclei in the central periblast, derived from the nucleus of the marginal cell. protrusions from the central periblast extend into the segmenta- tion cavity. Nuclei are often found in these protrusions, which suggest that cells are being added to the segmented part. This egg is still in the cleavage stage, being twenty to twenty-two hours before gastrulation [considering the time of gastrulation five to seven hours before laying as determined by Mr. Patter- son (7)], and may therefore be considered not unlike the teleost egg. But in following through the successive later stages, simi- lar relations are found between periblast and blastodisc and there is no time when they are distinct. Fig. 10 shows in mere outline the conditions at the margin of. Fig. 10. Margin of a transverse section of a pigeon's egg about twenty and a half hours after fertilization, 4:25 P. M. , periblast 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; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-; Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report; HighWire Press. Lancaster, Pa. [etc. ] : Lancaster Press, inc. [etc. ]
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