160 ELEMENTARY HISTOLOGY 



ii. The interstitial lamellae fill up the spaces between 

 the Haversian systems. They form parts of circles 

 which are in many cases of much larger radius 

 than the circles of the Haversian systems. 



iii. The lacunae are the spaces in the matrix in which 

 the bone-cells lie. In sections of dried bone the 

 lacunse appear black, through being filled either 

 with air or with dirt. 



iv. The canaliculi are very fine branching canals con- 

 necting the lacunse 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 perimedullary lamellae are a series of concen- 

 tric lamellse lining the central medullary cavity 

 of the bone. 



