The papers collected in this volume represent the formal proceedings of the Third European Symposium on Calcified Tissues which was held in Davos, Switzerland from 11th to 16th April 1965 under the sponsorship of the Laboratorium fur experi mentelle Chirurgie, Schweizerisches Forschungsinstitut Davos. This Symposium fol lowed the now established tradition of the previous Symposia held in Oxford in 1963 and in Liege in 1964. Participation was again strictly on a residential hasis. This year the Schatzalp Hotel provided a scenic and secluded meeting place high on a mountain side overlooking Davos yet close to the Forschungsinstitut in which the opening session of the Symposium was held. The papers and communications published in the volume are arranged in order of presentation and are grouped under the five main themes selected for discussion by the Symposium, namely, "Cell function in the formation, maintenance and destruc tion of osseous tissue", "Response of calcified tissues to mechanical factors", "Mecha nisms of mineralization and diseases related to mineral deposition", "Hormones and bone" and "Fundamental structure of dental hard tissues". The programme consisted of a number of review lectures given by invited speakers and of short communications in relation to each of the above themes. No attempt was made to record the dis cussions to the papers as, being a residential meeting, the more valuable and interest ing interchanges took place informally in small discussion groups and not within the time schedule of the prearranged programme.

Session ICell Function in the Formation, Maintenance and Destruction of Osseous TissueChairmen: P. Gaillard, I. MacIntyre, H. J. Dulce, A. B. Borle

The Two Faces of Resorption
Some Remarks and Questions on Metabolic Patterns in the Family of Bone Cells
Remodelling of the Bone Matrix
The Origin of Bone Cells in Endochondral Ossification
RNA Synthesis in Growing Bone
Histochemical Studies of Chondrocyte Function in the Cartilage of the Mandibular Condyle of the Rat
Correlation between Morphological, Biochemical, and Biophysical Effects of Parathyroid Hormone on Cell Membranes
Vitamin D-ascorbic Acid Association in Bone Metabolism
Lysosomes and Cartilage Resorption in Organ Culture
Acid Hydrolases, Lysosomes and Bone Resorption Induced by Parathyroid Hormone.
Le forage des canaux de Havers
Experimental Studies of the Non-inflammatory Vascular Pannus
Urinary Pyrophosphate in Disorders of Bone Metabolism
Bone Formation and Resorption in Bone Disorders
Studies of Iliac Crest Bone from Controls and Patients with Bone Disease by Means of Chemical Analysis, Tetracycline Labelling and Histology
Session IIResponse of Calcified Tissues to Mechanical FactorsChairman: R. Amprino
Electro-mechanical Factors Regulating Bone Architecture
Topographic-quantitative Study of Bone Tissue Formation and Reconstruction in Inert Bones
Structure and Healing of Bone as a Response to Continuous and Discontinuous Strain and Stress
Rheological Considerations in the Physical Properties of Bone
Haemodynamic Data on the Osseous Circulation
The Influence of Muscle Blood-flow on the Circulation in Bones
Session IIIMechanisms of Mineralization and Diseases Related to Mineral DepositionChairmen: S. M. Partridge, B. Engfeldt, W. D. Armstrong, J. P. Aubert and H. C. G. Bauer
A Biomolecular Survey of Calcification
Bone Mineral Metabolism in the Rat
Physico-chemical Methods for the Identification of Microcrystalline Basic Calcium Phosphates Prepared in Vitro
Umwandlungsvorgänge bei Calciumphosphaten
Some Observations on the Nature of Bone Mineral
The Osteon Calcification as Revealed by the Electron Microscope
Collagen and Apatite in Hard Tissues and Pathological Formations from a Crystal Chemical Point of View
Studies of Calcification in Plants
Crystallographic Identification of Calcium Deposits as Regards to their Pathological Nature, with Special Reference to Chondrocalcinosis
Infrastructural and Crystallographic Study of Experimental Calcifications
Protein Phosphorus and Phosphokinases in Connective Tissue
The Relationship between Swelling of Hard Tissue Collagen in Acid and Alkali and the Presence of Phosphate Cross-links
Microradiographic and Histological Observations in Primary Vitamin D-resistant Rickets
Therapeutic Response and Effect on the Kidney of 100 Units Vitamin D Daily in Osteomalacia after Gastrectomy
Changes in the Activities of Plasma Acid and Alkaline Phosphatases during Egg Shell Calcification in the Domestic Fowl
Calcium Exchanges in the Aorta of the Rat
Estimation of the 24 Hour Exchangeable Calcium Pool in Children Using 48Ca
Transfert du calcium intestinal chez l'homme dans les maladies déminéralisantes de l'os
Absorption of Calcium in Man: Effect of Disease, Hormones and Vitamin D
Therapeutic Results in Renal Tubular Osteomalacia with Special Reference to Calcium Kinetics
Etude du métabolisme du calcium chez l'homme à l'aide de calcium 45: l'ostéopétrose et l'ostéopsathyrose
Calcium Clearance and Re-absorption in Patients with Osteoporosis,Renal Stone and Primary Hyperparathyroidism
Session IVHormones and BoneChairmen: P. Fourman and P. H. Henneman
Bony Targets of Non-"skeletal" Hormones
Hormones and Calcium Metabolism
Mode of Action of Calcitonin
Of the Influence of Thyroxine, Thiouracil, Cortisone, Estrogen and Testosterone on Endo- chondral Ossification Utilizing Autoradiography
The Effect of Cortisone and Anabolic Agents on Bone
Sites and Mode of Action of Growth Hormone
Intestinal Absorption and Skeletal Dynamic of Calcium in Acromegaly
Session VFundamental Structure of Hard Dental TissuesChairman: H. J. J. Blackwood
Ultrastructure of Human Dentin
Preliminary Studies of the Ultracentrifugal and Free Zone Electrophoresis Characteristics of Neutral Soluble Proteins of Bovine Embryo Enamel
The Development of Enamel Structure in Mammals.