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F. G. E. Pautard 



geneous fibrous protein which is the bulk of the organic substance oriented with bone 

 salts, but in the calcified keratins, which are also fibrous and also oriented, the horny 

 material of the "matrix" is not one protein, but a family of proteins, each of which 



Fig. 2. Comparison of X-ray Laue diffraction diagrams (CuK radiation, fibre axis vertical) from two pairs 



of structures of epidermal origin, a. Fringe fibre tip of baleen from BaLtenoptcriis horealis. h. Tips of anterior 



dorsal papillae from bovine tongue, c. Tip of chela of Squilla species, d. Tip of chela of Callinectes 



is comparable to collagen in a mechanical sense. Again, in the calcified chitins (for 

 instance Kelly et al., 1965) the principal oriented organic component is the poly- 

 saccharide, but protein In some unknown configuration is present also and in this 

 case the "matrix" consists of a complex partnership in which the protein tends to 

 diminish as calcification Increases. 



The diversity of organic molecules and macromolecules associated with calcium 

 salts prompts me to suggest the term topographical matrix to describe the skeletal, 

 usually fibrous, framework laid down In partnership with the mineral phase. This 

 term conveys the idea of an architectural arrangement of stable, frequently Insoluble 

 structures which are often oriented with the Inorganic crystals and which can be 

 distinguished from the more labile and sparse "ground substances" which fill the 

 Interstices of the fibrous network. The topographical matrix is related to the calcium 

 deposits in some way, but we are not committed to thinking of one macromolecule 



