Carpenter's principles of human physiology . ncephalon, and epen-cephalon; the formation of the amnion by the growth of two folds of theepiblast, and the growth of the allantois into its cavity differ in no essentialrespect from the similar processes in the chick, though the allantois neverattains the same degree of development in the mammal. A microscopic Transverse section through the Embryo of the Chick at theclose of the firpt day of incubation, magnified about 100 dia-meters :—eh, notochord or chorda dorsalis ; h, external serous layeror epiblast; m, medullary portion of epiblast ; Pv, me
Carpenter's principles of human physiology . ncephalon, and epen-cephalon; the formation of the amnion by the growth of two folds of theepiblast, and the growth of the allantois into its cavity differ in no essentialrespect from the similar processes in the chick, though the allantois neverattains the same degree of development in the mammal. A microscopic Transverse section through the Embryo of the Chick at theclose of the firpt day of incubation, magnified about 100 dia-meters :—eh, notochord or chorda dorsalis ; h, external serous layeror epiblast; m, medullary portion of epiblast ; Pv, medullarygroove between the dorsal lamina? Rf and m; dd, intestinalepithelial or glandular layer (hypoblast); mop, vertebral plate, inwhich the primary or proto-vertebrse are formed, and which iscontinuous with the mesoblast, sp; uwh, fissure in the mesoblast,presenting the first indication of the pleuro-peritoneal cavity, andof the subsequent division of this layer into two other layers. 920 OF GENERATION : EMBRYONIC DEVELOPMENT. Fig. examination of the Amniotic membrane in the Human subject shows that itconsists of an inner layer of tessellated epithelium, and an outer layer, whicheven at the fourth week presents spindle-shaped corpuscles, and at the seventhweek has become well-marked connective tissue. In some animals it is pro-vided with muscular fibres, and performs distinct movements but it never inany species possesses proper vessels. From its mode of formation, the Amnionis directly continuous with the skin of the embryo, and the Amniotic fluidin which the foetus floats occupies the space between the inner layer and theskin. 736. As the development of the embryo progresses, the walls of theabdomen and the coats of the intestines begin to be formed by the bendingdownwards and forwards of the lateral portions ofthe blastodermic vesicle, termed respectively thesomatopleure and the splanchnojAeure. In Fig. 842,the mode of the development of the abdominalcavity is seen
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectphysiology, bookyear1
