. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 352 STOMACH AND INTESTINE. free extremity of the villus:—to the contrac- tion of the muscular layer of which it would appear to be chiefly, though not wholly, due. The veins (vv,fg. 260.) come off from this network by the gradual union of capillaries in the upper half of the villus, so as to form two or more venous trunks. These are usually about double the width of the corre- sponding arteries : they run at a distance from them ; and often lie rather nearer to the surface of the villus. Below, these trunks become conflu
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 352 STOMACH AND INTESTINE. free extremity of the villus:—to the contrac- tion of the muscular layer of which it would appear to be chiefly, though not wholly, due. The veins (vv,fg. 260.) come off from this network by the gradual union of capillaries in the upper half of the villus, so as to form two or more venous trunks. These are usually about double the width of the corre- sponding arteries : they run at a distance from them ; and often lie rather nearer to the surface of the villus. Below, these trunks become confluent in the single vein of the process; which, passing vertically downwards, terminates by joining one of the numerous veins belonging to the venous plexus around the orifices of the intestinal tubes. And this latter network also joins that of the viilus by such numerous communications, that the two might almost be regarded as merging into each other. The substance which forms the ground- work or basis of the villus resembles, to some extent, that of the gastric mucous membrane ; — the morphological consti- tuents of which we have already seen to be indistinct, except at the bottoms of the tubes. It rarely presents any definite struc- ture. Sometimes, however, it is faintly striated. And occasionally this appearance is so marked, as to approach a fibrous character. In this re- spect, it resembles the papillae pf the skin and tongue ; — and, especially, those secondary projections which stud the fungi form papillae of the latter organ, the basis of which contains no yellow elastic fibres, but is almost homo- geneous, and often indistinctly granular. Mixed with this indistinctly fibrous tissue are numerous delicate cytoblasts or nuclei (b, Jigs. 259, 261, 262, 263.). The larger of these attain the size of coloured blood-cor- puscles ; while the small merge into granules by increasing minuteness. The exact, re- lation of these to the basis of the villus is un- known. Their g
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