File:Animal and vegetable physiology, considered with reference to natural theology, by Peter Mark Roget (1834) (14776666184).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

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:
onstituted. In the cylindrical bones, the spicula prevail,and they are arranged longitudinally, and pa-rallel to one another, and to the axis of the bone.They first constitute a ring in the middle of itslength: this ring enlarges in all its dimensions,but principally in its length; the spicula be-coming larger, not by the stretching of theirparts, in consequence of the insinuation of freshmaterials between those already deposited, butby the addition of new particles at both theirextremities. In like manner, the ring increasesin thickness, not by the deposition of phosphateof lime between the original layers, but by theapplication of fresh layers on the outside ofthose already existing. In the flat bones, the process of ossification isvery similar to what I have just described; only OSSIFICATION. 379 the fibres have a radiated arrangement, shootingout from the spot where the first deposit tookplace, as from a common centre. This is seenin Fig. 174, which represents the parietal bone of
Text Appearing After Image:
the human skull, in an early stage of its ossifi-cation, and shows the radiating fibres very dis-tinctly. In the cubical, and more irregularlyshaped bones, the process is, doubtless, con-ducted with the same order and regularity, al-though it cannot so readily be followed by theeye. The same process is repeated in differentparts of the bone, wherever nature has, in con-formity with determinate laws of developement,appointed particular centres of ossification. Thebone continues to extend from each of these cen-tres, proceeding gradually towards the circum-ference, or the remoter parts of the cartilage, onwhich the ossific materials are moulded, and bythe form of which that of the future bone isregulated. The process of ossification has, how- 380 THE MECHANICAL FUNCTIONS. ever, this peculiarity, that the cartilage is pro-gressively absorbed to make room for the depo-sits of bony substance. When the bone is long,separate points of ossification appear in the ex-tremities, before the centr

Note About Images