BONE. 49 



iv. The canaliculi are very fine branching canals con- 

 necting the lacunae together : they are occupied 

 while the bone is living by branching processes 

 of the bone-cells. At the outer part of each 

 Haversian system, some of the canaliculi are 

 looped, opening at both ends of the loop into 

 the same lacuna. 



V. The large central medullary cavity of the bone is 

 occupied during life by the marrow, which 

 consists of adipose tissue, with very numerous 

 bloodvessels and large nucleated reddish marrow 

 cells. 



vi. The peripheral or circumferential lamellae are a 



series of concentric lamellae parallel to the surface 

 of the bone, and forming its most superficial 

 layer. 



vii. The perimeduUary lamellae are a series of concen- 

 tric lamellae lining the central medullary cavity 

 of the bone. 



E 



