The development of the human body; a manual of human embryology . 88 THE DEVELOPMENT OF THE HUMAN BODY. were still widely open. The embryo will be seen from thefigure to project somewhat both in front of and behind theyolk-sac, although the greater part of its ventral surface isstill formed by that structure. At the sides also it is wellseparated from the yolk-sac, and resting upon the sac infront is a swelling which represents the heart. In another embryo (Fig. 41), slightly smaller though. Fig. 41.—Reconstruction of Embryo mm. , Allantois; am, amnion; B, belly-stalk; ch, chorion;

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The development of the human body; a manual of human embryology . 88 THE DEVELOPMENT OF THE HUMAN BODY. were still widely open. The embryo will be seen from thefigure to project somewhat both in front of and behind theyolk-sac, although the greater part of its ventral surface isstill formed by that structure. At the sides also it is wellseparated from the yolk-sac, and resting upon the sac infront is a swelling which represents the heart. In another embryo (Fig. 41), slightly smaller though. Fig. 41.—Reconstruction of Embryo mm. , Allantois; am, amnion; B, belly-stalk; ch, chorion; h, heart; ms,mesodermic somite; os, oral fossa; ph, pharynx; v, chorionicvilli; Y, yolk-sac.—(After Etemod.) evidently older than the preceding one, and describedby Eternod, the edges of the medullary folds have not onlycome into contact throughout the greater portion of theirlength, but they have fused together, the groove betweenthem being open only in front and behind. On each sideof the median line eight somewhat oblong areas are to be THE EXTERNAL FORM OF THE BODY. 89 distinguished, caused by a transverse division of the sub-jacent mesoderm into what are termed mesodermic somites am

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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902