. The physiology of the domestic animals; a text-book for veterinary and medical students and practitioners. Physiology, Comparative; Domestic animals. 1 2 3 Fig. View of the Kakxy Stages of Segmentation iv a Fowl s Egg, after Custk. (Foster and Balfour.) „f fi!/8rr0',ent,8 f!1? earlira* a'a«0; Th° «"' furrow, B, has begun to make its appearance in the centre of the germinal dlsk, whoso periphery is marked l,y the line A. In 2 the first furrow is competed across the disk, and a second similar furrow at nearly right angles to the first has apr>e° red The disk tin? becomes d
. The physiology of the domestic animals; a text-book for veterinary and medical students and practitioners. Physiology, Comparative; Domestic animals. 1 2 3 Fig. View of the Kakxy Stages of Segmentation iv a Fowl s Egg, after Custk. (Foster and Balfour.) „f fi!/8rr0',ent,8 f!1? earlira* a'a«0; Th° «"' furrow, B, has begun to make its appearance in the centre of the germinal dlsk, whoso periphery is marked l,y the line A. In 2 the first furrow is competed across the disk, and a second similar furrow at nearly right angles to the first has apr>e° red The disk tin? becomes divided somewhat irregnlarly into quadrants by four (half) fVrrows In a later stam\ t » mendian furrows, B, have increased in number, from four, as in B. tonineand cross fiSowSave also Wrii""' WW*™}""1- T|M disk !? «™ ™t up into small central, C, and larger D per ipC 1 segmeni Several new cross-furrows are seen jnst beginning, as ex. gr., close to the end of til" iff,?%relrence, D About the time the shell is being formed, provided impregnation has taken place, changes occur in the blastoderm, which, though analo- gous to the process of segmentation already mentioned as takino- place in the mammalian ovum, yet differs from it. The germinal vesicle first disappears, and a furrow is then seen to run across the germinal disk dividing it into two halves. This furrow is then met by a second run- ning at right angles to the first; this is then crossed by another and division of the segments proceeds rapidly by furrows 'running in all directions until the germinal mass is cut up into an immense number of minute masses of protoplasm, smaller toward the centre than at the periphery of the disk. The furrows thus formed are not merely superficial, but extend through the entire thickness of the germinal disk: hence the germinal disk >s cut up into minute masses of protoplasm. In other words, a. Please note that these images are extracted from scanned
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectphysiol, bookyear1890
