File:Animal and vegetable physiology, considered with reference to natural theology, by Peter Mark Roget (1834) (14798947893).jpg

Identifier: animalandvegetab01roge (find matches)
Title: Animal and vegetable physiology, considered with reference to natural theology, by Peter Mark Roget ..
Year: 1834 (1830s)
Authors: Roget, Peter Mark, 1779-1869
Subjects: Biology Physiology Plant physiology Natural theology
Publisher: London : W. Pickering
Contributing Library: University of California Libraries
Digitizing Sponsor: MSN

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ng the parttowards the apex of the former cone, and ex-tending farther towards the base. Hence alongitudinal section of the whole presents theappearance represented in the annexed figures(218*), where a is the section of the horn of anOx, and b, a similar section of the horn of anAntelope. C is a magnified view of the extre-mity of the latter, together with a portion of thebone D, which occupies the axis of the horn. In this process of the formation of horn, ashappens in that of shells, there sometimes occurirregularities, or periodical intermissions andincrease of action in the secreting organs, givingrise to transverse grooves, or ridges. Thesemay be seen in the horns of the goat, in whichthe fibres are short, and laid one over anotherwith the same regularity as the tiles of a house.The tendency in these horns to assume a spiralform is explicable on the same principles as RUMINANT QUADRUPEDS. 515 those which regulate the growth of turbinatedshells. The horns of the ox and of the an-
Text Appearing After Image:
telope tribes are formed of longer and morecontinuous fibres, w hich are closely compactedtogether, and exhibit very distinctly the seriesof hollow cones of which they are composed. The horns of the Rhinoceros^ both of the oneand two homed species, grow from the integu-ment covering the nose, to which they adherewithout having any connexion with the subja-cent bones. They have a pyramidal shape,and are composed of parallel fibres, resembling .516 THE MECHANICAL FUNCTIONS. hairs, agglutinated together into a solid massby a material which acts as a cement. Thisfibrous structure is most distinctly seen at thebase of the horn, where the ends of the fibresproject, like those of a brush, from the surface.When these horns are sawn transversely, and exa-mined with a magnifying glass, a great numberof orifices are seen, marking the empty spacesthat intervene between the hairs ; and if the sec-tion be made in a longitudinal direction, the samespaces give rise to the appearance of parallelgroove

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