[Significance of the haversian number].

The aim of this work is to show that the measurement of the haversian number, i.e. the number of haversian canals per unit surface in transverse sections of compact bone, is not suffisantly accurate to determine the degree of compact bone remodelling. At the beginning of adult life, the aspect of the interstitial bone indicates that one haversian canal can correspond to one to four osteons (fig. 1). With increasing age, the diameter of the osteons decreases (fig. 2) and, consequently, for a same remodelled surface of bone the number of haversian canals varies greatly. In the elderly, the dissociation between osteon production and that of haversian canals increases (fig. 3). Moreover, the presence of large, irregular cavities which are difficult to assimilate to one or more haversian canals tends also to diminish, in terms of remodeling, the significance of the haversian number.