BONE 71 



In compact bone, the blood-vessels run in a line parallel with 

 the long axis of the bone, in branching inosculating channels 

 (averaging about 50 /><< in diameter) the Haversian canal*. The 

 lamellae of osseous tissue are arranged concentrically around these 



FIG. 47. SECTION OF BONE SHOWING SHARPEY'S FIBERS PULLEK OUT ov POSITION. 



AFTER H. M TILLER. 



canals. A single Haversian canal, and the lamella? surrounding 

 and belonging to it, constitute a Haversian system. 



The lamellae beneath the periosteum are not arranged as above, 

 but parallel with the surface of the bone. These plates are per- 

 forated at a right angle and obliquely by blood-vessels from the 



FIG. 48. DIAGRAM OF A HAVERSIAN CANAL. 



A. Artery. 



B. Vein. 



C. Nerve. 



D. D, D. Lymph-channels. 



periosteum, as they pass on their way to the Haversian canals. 

 These lamellae are also perforated by partly calcined connective 

 tissue the perforating fibers of Sharpey. (Fig. 47.) 



A Haversian canal contains (Fig. 48) an artery, a venule, 

 lymph -channels, and a nerve -filament. The whole is supported 

 by connective tissue cells with delicate processes. The walls 



