Image from page 376 of "Natural history" (1907)
Title: Natural history
Identifier: cu31924012490771
Authors: National Antarctic Expedition, 1907-1904; Fletcher, Lazarus, Sir 1854-1921; Bell, F. J. (Francis Jeffrey), 1855-1924; British Museum (Natural History)
Subjects: Geology; Zoology; Botany
Publisher: London, Printed by order of the Trustees of the British Museum
Contributing Library: Cornell University Library
Digitizing Sponsor: MSN
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Text Appearing Before Image:
W. p. PYCRAFT. neossoptiles represent distinct feather generations, and that therefore the pre-pennse, as I have elsewhere (11) called those neossoptiles preceding contour feathers, are not, as some apparently hold, a part of—" agents in advance " of—the contour feathers which succeed them. Consequently, the fact that the bulk of the rami of the pre-pennae in Pygoscelis adelise are directly attached to the tips of the rami of the after-shaft of the succeeding teleoptile is a somewhat remarkable fact, especially since in all other instances yet known the nestling-down, when attached to contour feathers, is attached to the rami of the main shaft. In the case now under discussion the rami of the pre-penna, which are borne by the main axis of the contour feather, are few in number and take no appreciable part in the formation of the pre- penna as a whole, which is composed of rami connected by means of the long ribbon-shaped stalk with the rami of the aftershaft, and forming the large tuft of woolly down such as is seen in Fig. 3. The significance of this relation to the aftershaft must be referred to again later. Microscopically the rami of these " pre-pennse " are of considerable length, and have short, ribbon-shaped spirally-twisted radii which bear only about four pairs of minute fila. The spiral twist acts as a kind of felting arrangement, whereby the downy covering is " knitted," as it were, into an almost homogeneous coat. The Nestling Boion of the Emperor Penguin. This differs not only in colour but also in certain small structural details from that of the Ad^lie Penguin. The first down-plumage differs from that which follows, in that it is short, barely covers the body, and resembles silky hair more than feathers; that is to say, when superficially examined. Under the microscope each down feather is found to be made up of several rami, umbelliform in arrangement, and of moderate length, each ramus being produced into a long filament beyond the radii, which are short. The fila of these radii are much larger than in Pygoscelis. This first down-plumage is rapidly succeeded by similar umbelliform tufts of much greater length and volume. The rami are about twice as long as those which preceded them, but the radii are only, relatively, slightly longer, and bear from eight to ten pairs of fila. This generation of down feathers differs from the corresponding generation in Pygoscelis, firstly, in that the radii are straight instead of spirally twisted, so that the down is less " felted," and secondly, in that instead of being of a uniform character throughout, the rami of the down
Text Appearing After Image:
PIG. 4.—THE FIRST (NEOSSOPTYLE) AND SECOND (mESOPTYLE) DOWN FEATH- ERS OF Aptenodytes forsteri. M = MESOPTYLE.
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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 work.
Image from page 376 of "Natural history" (1907)
Title: Natural history
Identifier: cu31924012490771
Authors: National Antarctic Expedition, 1907-1904; Fletcher, Lazarus, Sir 1854-1921; Bell, F. J. (Francis Jeffrey), 1855-1924; British Museum (Natural History)
Subjects: Geology; Zoology; Botany
Publisher: London, Printed by order of the Trustees of the British Museum
Contributing Library: Cornell University Library
Digitizing Sponsor: MSN
View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.
Text Appearing Before Image:
W. p. PYCRAFT. neossoptiles represent distinct feather generations, and that therefore the pre-pennse, as I have elsewhere (11) called those neossoptiles preceding contour feathers, are not, as some apparently hold, a part of—" agents in advance " of—the contour feathers which succeed them. Consequently, the fact that the bulk of the rami of the pre-pennae in Pygoscelis adelise are directly attached to the tips of the rami of the after-shaft of the succeeding teleoptile is a somewhat remarkable fact, especially since in all other instances yet known the nestling-down, when attached to contour feathers, is attached to the rami of the main shaft. In the case now under discussion the rami of the pre-penna, which are borne by the main axis of the contour feather, are few in number and take no appreciable part in the formation of the pre- penna as a whole, which is composed of rami connected by means of the long ribbon-shaped stalk with the rami of the aftershaft, and forming the large tuft of woolly down such as is seen in Fig. 3. The significance of this relation to the aftershaft must be referred to again later. Microscopically the rami of these " pre-pennse " are of considerable length, and have short, ribbon-shaped spirally-twisted radii which bear only about four pairs of minute fila. The spiral twist acts as a kind of felting arrangement, whereby the downy covering is " knitted," as it were, into an almost homogeneous coat. The Nestling Boion of the Emperor Penguin. This differs not only in colour but also in certain small structural details from that of the Ad^lie Penguin. The first down-plumage differs from that which follows, in that it is short, barely covers the body, and resembles silky hair more than feathers; that is to say, when superficially examined. Under the microscope each down feather is found to be made up of several rami, umbelliform in arrangement, and of moderate length, each ramus being produced into a long filament beyond the radii, which are short. The fila of these radii are much larger than in Pygoscelis. This first down-plumage is rapidly succeeded by similar umbelliform tufts of much greater length and volume. The rami are about twice as long as those which preceded them, but the radii are only, relatively, slightly longer, and bear from eight to ten pairs of fila. This generation of down feathers differs from the corresponding generation in Pygoscelis, firstly, in that the radii are straight instead of spirally twisted, so that the down is less " felted," and secondly, in that instead of being of a uniform character throughout, the rami of the down
Text Appearing After Image:
PIG. 4.—THE FIRST (NEOSSOPTYLE) AND SECOND (mESOPTYLE) DOWN FEATH- ERS OF Aptenodytes forsteri. M = MESOPTYLE.
Note About Images
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 work.