HAVEKSIAN SYSTEMS 



169 



nerve fibres, and peri vascular lymphatics. Concentrically arranged 

 around the Haversian canal are parallel layers of dense fibrous 

 ft tissue, the Haversian lamellae. 



The fibre bundles of this tissue 

 form an interlacing network 

 whose bundles frequently cross 

 each other at right angles and 

 whose interstices are occupied 

 by a solid calcareous mass, con- 



FIG. 162. TRANSECTION THROUGH THE COM- 

 PACT BONY WALL OF A HUMAN META- 

 CARPAL BONE. 



a, outer circumferential lamella? ; 6, in- 

 ner circumferential lamella? ; c, Haversian 

 canals ; d, interstitial lamellse ; e, lacunae, 

 with delicate radiating canaliculi. From 

 a thin section of ground bone. x 90. 

 (After Kolliker.) 





FIG. 163. LONGITUDINAL SECTION OF 

 GROUND BONE FROM THE SHAFT OF 

 THE HUMAN FEMUR. 



a, Haversian canals ; 6, lacunae ; c, cana- 

 liculi. x 100. (After Kolliker.) 



sisting chiefly of the phosphates and carbonates of calcium. 

 From four to twenty such calcareous lamellse are found in each 

 Haversian system. 



Both in and between the lamellae are many small ovoid spaces 

 which are partially filled by small flattened cells, the bone corpus- 

 cles : these spaces are known as the lacuna. From each lacuna 



