22O 



MOTION AND COORDINATION 



than the canaliculi and contain small nerves and blood 

 vessels, chiefly capillaries (Fig. 95). They extend length- 

 wise through the bone. The canaliculi are channels for 

 conveying lymph. They pass out from the Haversian 

 canals at right angles, going to all por- 

 tions of the compact substance except a 

 thin layer at the surface. In the surface 

 layer of the bone the canaliculi are in 

 communication with the periosteum. 

 The Bone Cells. Surrounding the 



Haversian canals are thin layers of bone 

 showing Haversian 



canal and contents, substance called the lamina, and within 

 highly magnified (af- these are great numbers of irregular 

 terSchafer). i. Arterial bodieS) known as the lacunce. The walls 



capillary! ^NewT of the lacunse are hard and dense, but 

 bers. 4. Lymph vessel, within each is an open space. In this 

 lies a flattened body, having a nucleus, 

 which is recognized as the bone cell, or the bone corpuscle 

 (Fig. 96). It appears to be the work of the bone cells to 

 deposit mineral matter in the walls 

 surrounding them and in this way to 

 supply the properties of hardness and 

 stiffness to the bones. The canaliculi 

 connect with the lacunae in all parts 



of the bone, causing them to appear 



FIG. 96. Bone cell 

 under the microscope like so many removed from the lacuna 



burs fastened together by their pro- and very highly magni- 

 jecting spines (Fig. 94). fied - ( From Quain's 



How the Bone Cells are Nourished. - 



The bone cells, like all the other cells of the body, are 

 nourished by the lymph that escapes from the blood. 

 This passes through the canaliculi to the cells in the dif- 

 ferent parts of the bone, as follows : 



