I.] THE WHITE OF THE EGG. 13 



eggs which have been kept for some time, whether incubated 

 or not, and gradually increases in size, as the white of the 

 egg shrinks in bulk by evaporation. 



3. Immediately beneath the shell-membrane is the white 

 of the egg or albumen (Fig. 1, w.), which is, chemically 

 speaking, a mixture of various forms of proteid material, 

 ■with fatty, extractive, and saline bodies. 



Its average composition may be taken as 

 12 'o p. c. proteid matter, 

 I '5 p. c. fat and extractives, 

 "5 p. c. saline matter, chiefly sodic and potassic chlorides, with phos- 

 phates and sulphates, 

 86'0 p. c. water. 



The white of the egg when boiled shews in section 

 alternate concentric layers of a transparent and of a finely 

 granular opaque material. In the natural condition, the layers 

 corresponding to these opaque layers are composed of more 

 fluid albumen, while those corresponding to the transparent 

 layers are less fluid, and consist of networks of fibres, con- 

 taining fluid in their meshes. The outer part of the white, 

 especially in eggs which are not perfectly fresh, is more fluid 

 than that nearer the yolk. The innermost layer, however, 

 immediately surrounding the yolk (Fig. 1, x.), is of the more 

 fluid finely granular kind. 



In eggs which have been hardened a spiral arrangement 

 of the white may be observed, and it is possible to tear off 

 laminae in a spiral direction from left to right, from the 

 broad to the narrow end of the esrg'. 



Two twisted cords called the Chalazce (Fig. 1, ch. I.), com- 

 posed of coiled membranous layers of the less fluid albumen, 

 run from the two extremities of the egg to the opposite 

 portions of the yolk. Their inner extremities expand and 

 merge into the layer of denser albumen surrounding the 

 fluid layer next the yolk. Their outer extremities are free, 

 and do not quite reach the outer layer of the white. Thus 

 they cannot serve to suspend the yolk, although they may 

 help to keep it in position, by acting as elastic pads. The 

 interior of each chalaza presents the appearance of a suc- 

 cession of opaque white knots; hence the name chalazae, 

 grandines (hailstones). 



4. The yolk is enclosed in the vitelline membrane 

 (Fig. 1, V. t), a transparent somewhat elastic membrane easily 



