. Comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates -- Anatomy. b FIG. 25.—Stereogram of part of developing contour feather; compare with fig. 24. b developing barbs; pc, pith cavity; per, periderm; s, rhachis. MAMMALS have a skin relatively thicker than have other verte- brates, both layers contributing to the thickness and the whole rather loosely attached to the lower tissues. There are numerous glands, and the hair, abundant in all orders except the whales and sirenians, is found in no other class. Other cuticular structures as horn and claws (p. 27) are widely distribu
. Comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates -- Anatomy. b FIG. 25.—Stereogram of part of developing contour feather; compare with fig. 24. b developing barbs; pc, pith cavity; per, periderm; s, rhachis. MAMMALS have a skin relatively thicker than have other verte- brates, both layers contributing to the thickness and the whole rather loosely attached to the lower tissues. There are numerous glands, and the hair, abundant in all orders except the whales and sirenians, is found in no other class. Other cuticular structures as horn and claws (p. 27) are widely distributed and scales occur in several forms. The corium is thick and composed of irregularly interlaced fibres with muscles, blood-vessels, etc. Its outer surface is frequently thrown into papillae or ridges, especially on the palms and soles, these carrying the epidermis with them. In the thick epidermis several strata may usually be recognized: at the base a thick Malpighian layer; then a thin stratum lucidum in which distinct cells cannot be recognized; and on the outside the stratum corneum. One or more others are sometimes present. As will readily be understood a cell passes through all of these layers before it is worn from the surface of the skin. Hair.—The epidermis takes the initiative in the formation of hair. It thickens in spots, the thickenings pushing into the corium and each being cupped at the tip, blood-vessels extending into the cup. The basal cells of the ingrowth, thus richly nourished, proliferate rapidly and the 3. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Kingsley, J. S. (John Sterling), 1854-1929. Philadelphia, P. Blakiston's son & co.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1912
