. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. OVUM. 63 - 1042'5 - 1029'5 Bauclrimont and St. Ange* are quite confir- matory of this view. They are as follows : — Sp. gr. of the External albumen - 104T „ Internal albumen „ Whole yolk- „ Upper part of yolk - 1027' „ Lower part of yolk - lOSl'S-j- The chalazae, being of greater specific gra- vity than even the inner layer of white, always float lowest ; but, being attached to the yolk near its poles, they hang down from these points. All these circumstances may be illus- trated very clearly by sections of eggs that hav
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. OVUM. 63 - 1042'5 - 1029'5 Bauclrimont and St. Ange* are quite confir- matory of this view. They are as follows : — Sp. gr. of the External albumen - 104T „ Internal albumen „ Whole yolk- „ Upper part of yolk - 1027' „ Lower part of yolk - lOSl'S-j- The chalazae, being of greater specific gra- vity than even the inner layer of white, always float lowest ; but, being attached to the yolk near its poles, they hang down from these points. All these circumstances may be illus- trated very clearly by sections of eggs that have been boiled in different fixed positions, as on the side, on the large and small end ; in which it will be found that, while the chalazae exer- cise a certain control over the position of the yolk, that portion of its surface containing- the cicatricula rises higher and expands more fully within the white than the opposite portion, while the chalazae gravitate towards the lower side. (See fg. 44.) Structure of the external parts of the egg. — The shell of the bird's egg is composed of a delicate basis of organised animal matter im- pregnated with the calcareous and earthy particles, the arrangement of which approaches to a crystalline appearance, but is probably of a different nature. This substance is porous, like concreted gypsum-plaster, and allows of evaporation and the mutual diffusion of gases through it in the same manner as that sub- stance ; while, by its strength and rigidity, it affords protection and support to the softer parts of the egg during incubation. The pores of the egg-shell may be easily stopped by any greasy or oily matter, or by melted wax or varnish ; and then all passage of moisture or air through the shell being pre- vented, the development of the embryo be- comes impossible. Eggs that have been oiled cannot, it is well known, be hatched ; but eggs may be kept for a considerable time — weeks, or even for months — by immersion in lim
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