The laws and mechanics of circulation, with the principle involved in animal movement . all the parts acting in concert by means of thecorrelation of the nerves in the medulla oblongata, or thesame as for expelling waste products in the rectum and blad-der, the principle being the same. And by looking from the placental sinuses to the special anat-omy in the placental tufts or villi (Fig. 138), it is readilyperceived how the pumping actions may be set up in them forpumping the fluids into and out of themselves, the same as in PHYSIOLOGICAL ANATOMY. 327 the lungs when the animal becomes an air-
The laws and mechanics of circulation, with the principle involved in animal movement . all the parts acting in concert by means of thecorrelation of the nerves in the medulla oblongata, or thesame as for expelling waste products in the rectum and blad-der, the principle being the same. And by looking from the placental sinuses to the special anat-omy in the placental tufts or villi (Fig. 138), it is readilyperceived how the pumping actions may be set up in them forpumping the fluids into and out of themselves, the same as in PHYSIOLOGICAL ANATOMY. 327 the lungs when the animal becomes an air-breather at the endof the intra-uterine term, perfect freedom of action beingalike secured in both, and the same law applying for produc-ing afflux and efflux of the fluids ; but a still more close re-semblance is furnished in the villi of the intestinal canal;only that muscles are added in the latter for producingmore energetic action and a larger amount of work tomake it commensurate with the force expended in the organ-ism. Still, it is manifest from the special anatomy in these. Fig. 137.—Vertical Section of Placenta, showing arrangement of maternal and fcetalvessels.—Dalton. a, a, Chorion; 6, 6, decidua ; c, c, c, c, orifices of uterine sinuses organs, that absorption must go on energetically. Thus,under the epithelium {a, a) we have a basis of connective tissuefibres (c, c) running longitudinally from end to end of theorgan, and by expanding and contracting a pumping actionmust inevitably be produced in the organ for aspiratingand propelling the fluids to and from the foetus and thesinuses, all the villi acting in concert. The vascular loopsbeing placed within the band of connective-tissue fibres (b,c, c), must necessarily undergo rhythmical compressionduring contraction, thereby increasing pressure in them,causing the blood to flow into the umbilical vein ; whileduring expansion the opposite obtains, causing the fluids toflow into the vessels from the sinuses and umb
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Keywords: ., bookcentury1800, bookde, booksubjectblood, booksubjectrespiration
