. A manual of zoology. Zoology. IV. VERTEBRATA: AVES are claws, but as a rule the fingers are feathered. On most places the skin is soft and thin, since corium and stratum corneum are poorly devel- oped. Periodic molts of the integument do not occur, since the horny layer, as in mammals, undergoes a constant renewal. These peculiarities of the skin are correlated with the appearance of the protecting plumage. The feather, like the hair of mammals, is exclusively epithelial in character, but is a much more complicated structure. The cornified epithelium forms a firm axis, the scape, from w
. A manual of zoology. Zoology. IV. VERTEBRATA: AVES are claws, but as a rule the fingers are feathered. On most places the skin is soft and thin, since corium and stratum corneum are poorly devel- oped. Periodic molts of the integument do not occur, since the horny layer, as in mammals, undergoes a constant renewal. These peculiarities of the skin are correlated with the appearance of the protecting plumage. The feather, like the hair of mammals, is exclusively epithelial in character, but is a much more complicated structure. The cornified epithelium forms a firm axis, the scape, from which, right and left arise branches, or barbs. The scape is solid as far as the barbs extend (rachis, or shaft), while below it is hollow {quill, or calamus). The quill is inserted deep in a follicle in the corium and is provided with muscles for its movement. Its hollow in most fully developed feathers is empty. 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 Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterling), 1854-1929, ed. and tr. New York, H. Holt
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
