File:Animal and vegetable physiology, considered with reference to natural theology, by Peter Mark Roget (1834) (14778504832).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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ith its bulbous root, de-tached from the body ; and Fig. 34, a transversesection magnified. The bulb itself is containedin a distinct cell, shown at a. Fig. 35, whichrepresents a longitudinal section of these organs.This cell contains a portion of fat in which thenumerous vessels supplying its pulp and capsuleare embedded. The bulb is itself surroundedby an outer sheath, s, into the cavity of which,B, there opens a duct, d, proceeding from a smallcell or follicle, f, lodged in the cellular substanceon the outside of the sheath. This upper cellcommunicates below with another cavity, c. * See F. Cuviers Memoir on the Formation of the Quillsof the Porcupine, in the Nouvelles Annales du Museum, I. 429. ANIMAL ORGANIZATION. containing an unctuous matter 121 During the formation of the quill this unctuous matter issupplied through this channel, and probablyenters as an ingredient in its composition. Thecapsule of the pulp consists of two membranes,the one enveloping the other. Fig. 36 shows
Text Appearing After Image:
the bulb laid open by dividing the membranesand turning them aside. The horny portionof the quill is secreted by the internal mem-brane, I, and deposited in successive laminse.The external membrane is seen at o. Tliepulp itself, seen at p, is still more curiouslyorganized ; its surface being fluted, or formedinto longitudinal processes. The horny matter,being deposited on these processes, is mouldedto their shape, and concretes into laminae whichconverge from the circumference of the cylin-der towards the centre. The section (Fig. 36) 122 THE MECHANICAL FUNCTIONS. shows these converging laminae, which beingof a dark colour, give to the surface of thequill the appearance of being grooved; this,however, is merely an optical illusion, occasionedby the dark laminae being seen through thetransparent exterior covering ; as may readily bedetected by viewing the surface with a magni-fying glass.* After a certain period of the growthof the quill, the pulp ceases to supply the ma-terials for fo

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