The elements of Embryology (1889) The elements of Embryology elementsofembryo00fostuoft Year: 1889 I-J SEGMENTATION. Fig. 7. Surface View of the Germinal Disc op a Hen's Egg DURING THE LATER StAGES OF SEGMENTATION. (Chromic Acid Preparation.) At c in the centre of the disc the segmentation masses are very small and numerous. At b, nearer the edge, they are larger and fewer; while those at the extreme margin a are largest and fewest of all. It will be noticed that the radiating furrows marking off the segments a do not reach to the extreme margin e of the disc. The drawing is completed in o
The elements of Embryology (1889) The elements of Embryology elementsofembryo00fostuoft Year: 1889 I-J SEGMENTATION. Fig. 7. Surface View of the Germinal Disc op a Hen's Egg DURING THE LATER StAGES OF SEGMENTATION. (Chromic Acid Preparation.) At c in the centre of the disc the segmentation masses are very small and numerous. At b, nearer the edge, they are larger and fewer; while those at the extreme margin a are largest and fewest of all. It will be noticed that the radiating furrows marking off the segments a do not reach to the extreme margin e of the disc. The drawing is completed in one quadrant only ; it will of course he understood that the whole circle ought to be filled up in a precisely similar manner. In this way, by repeated division or segmentation, the original germinal disc is cut up into a large number of small rounded masses of protoplasm, which are small- est in the centre, and increase in size towards the peri- phery. The segments lying uppermost are moreover smaller than those beneath, and thus the establishment of the two layers of the blastoderm is foreshadowed.
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