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The structure and some physical properties of the testudinian eggshell.
Author(s) -
YOUNG J. D.
Publication year - 1950
Publication title -
proceedings of the zoological society of london
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0370-2774
DOI - 10.1111/j.1096-3642.1950.tb00656.x
Subject(s) - aragonite , eggshell , calcite , shell (structure) , fowl , lamella (surface anatomy) , biology , zoology , crystallography , anatomy , chemistry , mineralogy , materials science , ecology , composite material
Summary.1 A revised account of the structure of the fowl's egg is given. It has been found that the layer previously described as amorphous (von Nathusius, 1861) and as composed of small interlaced calcite crystals by Stewart (1934), consists in fact of very large calcite crystals which enclose the ovo‐keratin foundation of the shell. It is also found that the shell exhibits no sphaerulite structure whatever. 2 The structure of the eggshell of four species of tortoise is described. 3 The inorganic part of these shells is composed of sphaerulites of aragonite. 4 The presence of pores in the fowl's egg is demonstrated by two different techniques. 5 Pores are absent from the eggs of Testudo graeca and T. radiata. They appear to be present in the shells of Emys orbicularis and Amyda euphratica.6 Rate of water loss is both absolutely and per unit of area less from the intact tortoise egg than from the intact fowl's egg. 7 These findings are discussed in relation to the mode of life of tortoises.