BONE. 



59 



the fione corpuscles, the bodies of which are projected into the cana- 

 liculi. 



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

 long axis of the bone, in branching inosculating channels (averaging 

 one-five hundredth of an inch) the Haversian canals. The lamellae 

 of osseous tissue are arranged concentrically around these canals. A 

 single Haversian canal with the lamellae surrounding and belonging 

 to it constitute an Haversian system. 



The lamellae beneath the periosteum are not arranged as above, but 



FIG. 44. TRANSVERSE SECTION OF PORTION OF A DRIED LONG BONE, SHOWING THE HAVERSIAN 



SYSTEMS. 



A, A, A. An Haversian system. 



B. Haversian canal. 



The lacunae, canaliculi, and Haversian canals all appear black in the section, as they are filled 

 with air and the bony fragments resulting from grinding of the section, x 60. 



parallel with the surface of the bone. These plates are perforated at 

 right angles, and obliquely by bloo>l- vessels from the periosteum, as 

 they pass on their way to the Haversian canals. These lamellae are 

 also perforated by calcific connective tissue the perforating fibres of 

 Sharpcy. 



An Haversian canal contains (Fig. 44) an artery, a venule, lymph 



