File:Lectures delivered before the Young Men's Christian Association (1846) (14778918491).jpg

Identifier: lecturesdelivere19youn (find matches)
Title: Lectures delivered before the Young Men's Christian Association
Year: 1846 (1840s)
Authors: Young Men's Christian Association (Great Britain)
Subjects: Young Men's Christian Association (Great Britain) Religion
Publisher: London : James Nisbet and Co.
Contributing Library: Princeton Theological Seminary Library
Digitizing Sponsor: Internet Archive

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iverging threads. The yolk is lighter than the white ; thesethreads are heavier, they are attached to opposite sidesof the yolk, and seem to be the axes in which the yolkturns : they are attached, however, below the true axis, onthe half opposite to that which bears the spot: sinking asthey diverge and expand in the white, they make their half ofthe yolk the heavier, the spot-bearing half the lighter ; and,as the spot is at the middle of the surface of its hemisphere,it is always uppermost. Now, this spot is the germ in whichdevelopment of the chick begins, and from which it spreads,under the incubating influence of the mother : the germis thus brought closest to the hot brooding skin of the sittinghen. The shell is convex and dome-like, to bear her weight.In the course of development, the chick requires to breathe :as the vital fire burns up, organic material is reduced tocarbon ; a membrane over which the blood spreads in anetwork of minute vessels, like a gill or lung, then extends
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IN HIS ANIMAL CREATION. 9 from the embryo to the inner side of the shell, between itand the white : the shell is made porous to allow the airaccess to this temporary respiratory organ ; and the oxygencombining with the carbon, it exhales as carbonic acid. Asthe chick approaches the period of its extrication, it is ableto breathe by its proper lungs, and in the vesica aeris, d, orcollection of air at the great end of the eggy it finds thewherewithal to begin its feeble inspirations, and to utter thelow chirp which may be heard just before it chips the shell.And how does it efiect • this % By means of a hard knobspecially formed upon the end of the upper beak, and which,after it has done its work, disappears. You may think it strange that any mind capable oftracing and comprehending the relations of these structuresand their effects—what, in physiology, we term their uses or functions, in the inability to make the matter under-stood by any other phraseology,—that any competent ana

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