Fig. 111. An ideal representation of the papillæ. 1, 1, The cutis vera. 2, 2, The papillary layer. 3, 3, The arteries of the papillæ. 4, 4, The veins of the papillæ. 5, 5, The nerves of the papillæ.
622. The sensitive layer of the skin is thin, soft, uneven, pinkish in hue, and composed of blood-vessels, which confer its various tints of red; and of nerves, which give it the faculty of sensation. The unevenness of this layer is produced by small, elongated, conical prominences, called Pa-pil´læ.
623. Each PAPILLA is composed of a minute artery, vein, and nerve. Some of the prominences are arranged in concentric 285 ovals, as may be seen on the ends of the fingers; others are more or less parallel, and pursue a serpentine course; some suddenly diverge, and again reunite, as may be seen in the palm of the hand. Papillæ are found in every part of the skin. Consequently, their number is very great.
How is leather formed? 622. What is the appearance of the sensitive layer? What causes the unevenness of this layer? Explain fig. 111. 623. Describe the papillæ.
624. The cutis vera contains not only Arteries, Veins, and Nerves but Lymphatics, Oil-Glands and Tubes, and Perspiratory Glands and Tubes.
Fig. 112.
Fig. 112. The arteries and veins of a section of the skin. A, A, Arterial branches. B, B, Capillary, or hair-like vessels, in which the large branches terminate. C, The venous trunk, collecting the blood from the capillaries.