The laws and mechanics of circulation, with the principle involved in animal movement . Fig. 141.—Anatomy of the Egg.—Jones, a, b. Air-vesicle ; 6, arrow indicating theposition of the central axis of the egg ; c, the yolk ; /. Purkinjean vesicle ; g,cicatricula ; h, thickening of the vitelline membrane ; e, canal leading to d, the cen-tral chamber of the Fig. 142.—Egg of Fowl in Process of Development, showing area vasculosa, with vitellinecirculation, terminal sinus, etc.—Dalton. According to His. the heart is developed by the coalescenceof a layer of the splanchnopleure with a similar
The laws and mechanics of circulation, with the principle involved in animal movement . Fig. 141.—Anatomy of the Egg.—Jones, a, b. Air-vesicle ; 6, arrow indicating theposition of the central axis of the egg ; c, the yolk ; /. Purkinjean vesicle ; g,cicatricula ; h, thickening of the vitelline membrane ; e, canal leading to d, the cen-tral chamber of the Fig. 142.—Egg of Fowl in Process of Development, showing area vasculosa, with vitellinecirculation, terminal sinus, etc.—Dalton. According to His. the heart is developed by the coalescenceof a layer of the splanchnopleure with a similar layer from thesomatopleure, the hollow cavity formed by the union being infree communication with the adjacent omphalo-meseraic to Foster and Balfour, the upper end of the heartis developed out of the mesoblast of the splanchnopleure, butincreases in length step by step at the expense of the con- PHYSIOLOGY OF THE CIKCULATIOX. B43 tinually coalescing omphalo-meseraic veins. Thus the fact isundeniable, that the heart is developed in the venous systemin connection with the vitellus. The rhythmical expansionsand contractions in this organ (the punctum saliens of earlyauthors) serve to pump the vitelline fluids in the bulbusarteriosus and the two aortse which are developing at the otherend of the heart. But for this air-cushion within t
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Keywords: ., bookcentury1800, bookde, booksubjectblood, booksubjectrespiration
