The elements of Embryology, (1874) The elements of Embryology, elementsofembryo74fost Year: 1874 12 THE HEN S EGG. [chap. 2. Lining the shell, is the shell-membrane, which is double, being made up of two layers; an outer thicker (Fig. 1, s. m.), and an inner thinner one (i. s. m.). Both of these layers consist of several laminae of felted fibres of various sizes, intermediate in nature between connective and elastic fibres. Fig. I. fl'7/M DiAGKAMMATIC SECTION OF AN UnINCUBATED FOWL'S EgO (modified from Allen Thomson). hi. blastoderm, w. y. white yolk. This consists of a central flask-
The elements of Embryology, (1874) The elements of Embryology, elementsofembryo74fost Year: 1874 12 THE HEN S EGG. [chap. 2. Lining the shell, is the shell-membrane, which is double, being made up of two layers; an outer thicker (Fig. 1, s. m.), and an inner thinner one (i. s. m.). Both of these layers consist of several laminae of felted fibres of various sizes, intermediate in nature between connective and elastic fibres. Fig. I. fl'7/M DiAGKAMMATIC SECTION OF AN UnINCUBATED FOWL'S EgO (modified from Allen Thomson). hi. blastoderm, w. y. white yolk. This consists of a central flask-shaped mass and a number of layers concentrically arranged around this. y. y. yellow yolk. v. t. vitelline membrane, x. layer of more fluid albumen immediately surrounding the yolk. w. albumen consisting of alternate denser and more fluid layers, ch. I. chalaza. a. ch. air-chamber at the broad end of the egg. This chamber is merely a space left between the two layers of the shell-membrane, i. s. m. internal layer of shell- membrane, s. m. external layer of shell-membrane, s. shell. Over the greater part of the egg the two layers of the shell-membrane remain permanently in close apposition to each other; but at the broad end they tend to separate, and thus to develope between them a space into which air finds its way. This air-chamber, as it is called, is not to be found' in perfectly fresh eggs, but makes its appearance in
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