108 F. G. E. Pautard 



blood flow in muscle affected the circulation in underlying bone and the physiological 

 implications of this are discussed. 



Acknowledgements 

 I wish to thank Sir Herbert Seddon, Dr. Angus McPherson, the Joint Clinical 

 Research Committee of the Institute of Orthopaedics and the National Fund for 

 Poliomyelitis Research for encouragement and help. 



References 



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Reumatismo 4, 371 (1952). 

 Heald, C. B.: An inquiry into the treatment of fibrositis with observations on vascular com- 

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 Shaw, N. E.: Observations on the intramedullary pressure and blood flow in bones. Clin. 



Sci. 24, 312 (1963). 

 — Observations on the physiology of the blood vessels in bone. Ann. roy. Coll. Surg. Engl. 



35, 214 (1964). 

 Trueta, J., and J. A. F. de Valderrama: Muscle contraction and intraosseous circulation. 



J. Bone Jt Surg. 47 B, 186 (1965). 

 TuBiANA, R., and J. Duparc: Prevention of thrombo-embolic complications in orthopaedic 



and accident surgery. J. Bone Jt Surg. 43 B, 7 (1961). 

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A Biomolecular Survey of Calcification 



F. G. E. Pautard 

 Astbury Department of Biophysics, Leeds University, Leeds, Yorksh., England 



Deposits of inorganic calcium salts are so familiar to biologists that they seldom 

 warrant close attention and are dismissed frequently as waste products. In spite of an 

 increasing awareness that mineralization is a highly organized process, however, it 

 is immediately apparent from the literature that we derive most of our ideas about 

 the ultrastructural basis of calcification from studies of bone. There is little correlative 

 data from other tissues containing calcium phosphate, and the few publications on 

 the molecular structures associated with calcium carbonate in invertebrates are suf- 

 ficient to emphasize the lack of information about the nature and genesis of the same 

 salt in plants. The present grossly unbalanced state of knowledge is best illustrated 

 by an appeal to mass. The investigations of calcium phosphate in vertebrates far 

 exceed all other studies of calcium salts, yet bone, dentine and enamel are the least 

 abundant mineralized tissues, constituting a fraction of a percent of the calcium 

 oxalate in plants, where the nature of the inorganic substances present seems to have 

 been neglected and where there appear to be no reports of the ultrastructure in the 

 literature. 



There is, therefore, only fragmentary evidence for any comparison of the molecu- 

 lar arrangements present in calcified structures throughout nature, and although each 

 type of calcium salt has a common basis in chemistry, it has yet to be demonstrated 

 that there is a common cellular plan of mineralization. 



