File:Animal and vegetable physiology, considered with reference to natural theology (1836) (14764442072).jpg

Identifier: animalvegetable01roge (find matches)
Title: Animal and vegetable physiology, considered with reference to natural theology
Year: 1836 (1830s)
Authors: Roget, Peter Mark, 1779-1869
Subjects: Biology Physiology Plant physiology Natural theology
Publisher: Philadelphia, Carey, Lea & Blanchard
Contributing Library: NCSU Libraries
Digitizing Sponsor: NCSU Libraries

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nd enabling the animal to flutter in the air, and to break itsfall during its descent from the branches of trees. Struc-tures of this kind are possessed by the Sciurus volans^ or 380 THE MECHANICAL FUNCTIONS. flying squirrel, and also by some other species of the samegenus. They are seen on a still larger scale in the Lemurvolans, or Galeopitheciis. The resistance which these broadexpansions of skin oppose to the air, when the limbs arespread out, enables the animal to descend in perfect safetythrough that medium from very considerable heights: butthese appendages to the body are mere parachutes, not wings,and none of the animals which possess them can, by theirmeans, and with the utmost efforts which their muscles arecapable of exerting, ever rise from the ground, or even sus-pend themselves for a moment in the air. The only quadruped that can properly be said to be en-dowed with the power of flying is the Bat. In this animalthe portions of the skeleton (f. Fig. 223) which correspond
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to the phalanges of the fingers are extended to an enormouslength, and the pectoral muscles, which move the anteriorextremities, are of extraordinary size and power. In thelarger species, each wing is at least two feet in length. Thefine membrane, which is spread between these lengthenedfingers, has its origin in the sides of the neck, and reachesall along the body to the extremities of the hinder legs,which it encloses in its folds. Thus, not only is the sur-face, by which it acts upon the air, sufiiciently extensive,but the muscular powder, by which its motions are effected,is adequate to give it those quick and sudden impulses whichare requisite for flying: and thus, although its structure istotally different from that of birds, it yet performs fully the BAT. 381 office of a real wing. The bat flies with perfect ease, evenwhile carrying along with it one or two of its young: it isnot, however, fitted for very long flights. The conformation of the skeleton is adapted to this newand

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