. Animal biology. Zoology; Biology. CLASS AVES 399 Air sacs do not lighten the bird's body to any appreciable extent when the bird is in the air, as is often stated, though they do lighten it when the bird is swimming. Another requirement of an airplane is the posses- sion of planes for support; in a bird the wings and tail furnish such planes, giving a broad surface for support and also being capable of adjustment. Fig. 274.—Beaks of birds. From mounted specimens. A, generalized beak of ring- necked pheasant. X J^. B, straining beak of canvasback duck. X %. C, spearing beak of bittern. X }4-
. Animal biology. Zoology; Biology. CLASS AVES 399 Air sacs do not lighten the bird's body to any appreciable extent when the bird is in the air, as is often stated, though they do lighten it when the bird is swimming. Another requirement of an airplane is the posses- sion of planes for support; in a bird the wings and tail furnish such planes, giving a broad surface for support and also being capable of adjustment. Fig. 274.—Beaks of birds. From mounted specimens. A, generalized beak of ring- necked pheasant. X J^. B, straining beak of canvasback duck. X %. C, spearing beak of bittern. X }4- D, probing beak of greater yellowlegs. X J^. E, beak of brown pelican. X J^. F, chisel-like beak of hairy woodpecker. X /i- G, carnivorous beak of Swainson hawk. X 3i- H, insectivorous beak of nighthawk. X ^i- I, insectivorous beak of myrtle warbler. X %? J, graminivorous beak of black-headed grosbeak. X ,?^. K. beak of red crossbill. X %. to variations in the direction and strength of the wind. A third necessity in such a machine is the development of a large amount of sustained power; this is secured by the great size of the flight muscles and by the very effective aeration of the blood, which results in rapid and continuous oxidation. The large size of the heart and the relatively great capacity of the blood vessels also contribute to the same end. Still other char- acteristics which contribute to the considerable and constant production of energy are the effectiveness of the processes of digestion and elimina-. 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 Wolcott, Robert Henry, 1868-1934. New York ; London : McGraw-Hill Book Company, Inc.
Size: 1583px × 1579px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcoll, booksubjectbiology, booksubjectzoology
