. The life-histories of the British marine food-fishes. Fishes; Fishes; Fishes. Fig. 23. Egg of Whiting with spathulate neurochord. Fig. 24. Egg of Cod with embryo. Lateral view. more posteriorly, as elongated or elliptical thickenings of the sensory layer of the epiblast, and a large fissure or chink develops in the centre. To return to the growing blastoderm as it covers the yolk, it is found that the thickened margin or rim bounds an aperture called the blastopore by embryologists, this aperture attaining its maximum when the margin of the blastoderm has reached the equator, and thereafter
. The life-histories of the British marine food-fishes. Fishes; Fishes; Fishes. Fig. 23. Egg of Whiting with spathulate neurochord. Fig. 24. Egg of Cod with embryo. Lateral view. more posteriorly, as elongated or elliptical thickenings of the sensory layer of the epiblast, and a large fissure or chink develops in the centre. To return to the growing blastoderm as it covers the yolk, it is found that the thickened margin or rim bounds an aperture called the blastopore by embryologists, this aperture attaining its maximum when the margin of the blastoderm has reached the equator, and thereafter decreasing in calibre as the rim advances towards the vegetal pole of the yolk (Fig. 23); the latter indeed in certain views bulges from the rim like an india-rubber ball in the fingers. The embryonic rim is used up in the formation of the embryo. The aperture or blastopore then becomes contracted, marked with radial lines or furrows, and finally closes. In eggs with oil-globules it is at this time that the globule becomes surrounded by the protoplasmic periblast-layer which envelopes the yolk. Only in one instance, and that probably abnormal, has the globule been found freely moveable in the. 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 M'Intosh, William Carmichael, 1838-1931; Masterman, Arthur Thomas, joint author. London, C. J. Clay and sons
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectfishes, bookyear1897
