. Journal of morphology. f immigration. In the later cleavage stages there is a tendency for the cleavagefurrows to become less distinct than formerly in the region ofthe vegetal pole, indicating a difficulty in sustaining the holo-blastic character of the cleavage in an egg so heavily laden withyolk; the same tendency is observed in Necturus. In late segmentation immediately preceding gastrulation thecleavage pattern enables one to predict the side on which theblastopore is to appear; the egg undergoes a slight rotation, ona horizontal axis at right angles to the median plane. 486 BERTRAM G.
. Journal of morphology. f immigration. In the later cleavage stages there is a tendency for the cleavagefurrows to become less distinct than formerly in the region ofthe vegetal pole, indicating a difficulty in sustaining the holo-blastic character of the cleavage in an egg so heavily laden withyolk; the same tendency is observed in Necturus. In late segmentation immediately preceding gastrulation thecleavage pattern enables one to predict the side on which theblastopore is to appear; the egg undergoes a slight rotation, ona horizontal axis at right angles to the median plane. 486 BERTRAM G. SMITH \III. (lASTRULATIOX AXD EARLY FORMATION OF THE EMBRYO A. Description hij nUiges Stage 11: (figs. 113 to 137 and 220 to 222). This stage extendsfrom the time of the first appearance of the blastopore as a shorthorizontal groove until its ends meet to form a complete eggs kept in their natural environment, gastrulation beginsabout seven days after fertilization and two days after the begin-ning of Stage
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Keywords: ., bookcentury1900, bookdecade1, booksubjectphysiology, bookyear1912
