. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine . Cuvieri (precaval veins); E,external iliac arteries; H. G,posterior cardinal vein; Ic,common iliac arteries; If. clefts ; R. A, right andleft, rootn of the aorta; S. S,branchial collecting trunksor veins ; ,S7>. subclavian ar-tery ; 8b, subclavian vein;Si, sinus venosus; V, ventri-cle ; VC, anterior cardinalvein; Vm, vitelline veins. left side the nature of the extension of partsalready marked out rather than theformation of entirely new ones. Thefollowing are the principal c
. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine . Cuvieri (precaval veins); E,external iliac arteries; H. G,posterior cardinal vein; Ic,common iliac arteries; If. clefts ; R. A, right andleft, rootn of the aorta; S. S,branchial collecting trunksor veins ; ,S7>. subclavian ar-tery ; 8b, subclavian vein;Si, sinus venosus; V, ventri-cle ; VC, anterior cardinalvein; Vm, vitelline veins. left side the nature of the extension of partsalready marked out rather than theformation of entirely new ones. Thefollowing are the principal changes :The bending of the head-end down-ward (cranial flexure) ; the turningof the embryo so that it lies on itsthe completion of the vitelline circulation ; the in- THE DEVELOPMENT OF THE EMBRYO ITSELF. 105 crease in the curvature of the heart and its complexity of struct-ure by divisions ; the appearance of additional aortic archesand of the cardinal veins ; the formation of four visceral cleftsand five visceral arches ; a series of progressive changes in AAA. Fig. 109.—Diagram of circulation of yelk-sac at end of third day (Foster and Bal-four). Blastoderm seen from below. Arteries made black. H, heart; AA, sec-ond, third, and fourth aortic arches; A 0, dorsal aorta; , left vitellineartery; A. right vitelline artery; 8. T. sinus terminalis; L. of, left vitellinevein; R. of, right vitelline vein; S. V, sinus venosus ; D. C, ductus S. Ca. V, superior cardinal or jugular vein; V. Ca, inferior cardinal vein, Cuvicri; the organs of the special senses, such as the formation of thelens of the eye and a secondary optic vesicle ; the closing in ofthe optic vesicle ; and the formation of the nasal pits. In theregion of the future brain, the vesicles of the cerebral hemi-spheres become distinct; the hind-brain separates into ceie- 106 COMPARATIVE PHYSIOLOGY.
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1890
