The laws and mechanics of circulation, with the principle involved in animal movement . lliAnd it will be seen that here also there is a great contrastin the size of the arterial feeders and the discharging vesselsor veins (a, c), the veins being out of proportion to the arterialfeeders, the import of which has already been stated. Now,then, between these vascular loops and the liquids to be ab-sorbed is the layer of columnar epithelium ; and the question 216 PHYSIOLOGICAL ANAIOMY before us concerns the manner tins barrier is passed, or bowfat, albumen and other non-dialyzable substances effec
The laws and mechanics of circulation, with the principle involved in animal movement . lliAnd it will be seen that here also there is a great contrastin the size of the arterial feeders and the discharging vesselsor veins (a, c), the veins being out of proportion to the arterialfeeders, the import of which has already been stated. Now,then, between these vascular loops and the liquids to be ab-sorbed is the layer of columnar epithelium ; and the question 216 PHYSIOLOGICAL ANAIOMY before us concerns the manner tins barrier is passed, or bowfat, albumen and other non-dialyzable substances effect a rapidpassage into the interior of the cells, the membrane (membranapropria) beyond, and so get into the interior of the villi to thecapillaries and central lacteal. Furthermore, keep the fact inmind that the fat is simply emulsified, not saponified, whilealbumen passes in freely unchanged, especially when given inlarge quantities, thereby showing conclusively the existenceof a mechanical force for compelling them through themembranes; otherwise is inexplicable. This mechanics is. Fig. 80.—Vascular System of an Intestinal Villus in the Rabbit, a, The arteries(shaded), breaking up first into a capillary network around the glands of Lieberkuhn(d) ; b, network of capillaries in the villus ; c, venous vessels (unshaded).—Frey. also easily understood. Thus, the columnar epithelia arecovered by a perforated lid of thickened epithelium(Fig. bl, a, b), which acts as a sieve or colander for strain-ing the chyle, while the muscular cylinder contractsfor forcing it into the epithelia. whence it is passed in duetime into the parenchyma of the villi, and compelled thenceinto the capillaries and the central lacteal, the coarser par-ticles passing by the vessels into the latter, which functionsas a drainage system to the villi. The lids fit neatly over thesurface of the cells, and being in close apposition and firmlyconsolidated by animal cement, which fills up the interstices PHYSIOLO
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