INTRAMEMBRAXOUS OSSIFICATION 183 



the enchondral bone in the scarcity of its cellular elements ; other- 

 wise the process of intramembranous bone formation is identical 

 with that which forms the periosteal layers of the enchondral 

 bone. 



The after absorption of the bony spicules and partitions in 

 intramembranous bone is very active, the osteoclasts appearing in 

 considerable numbers. The contour of these bones is subject to 

 frequent changes as a result of the continued absorption and new 

 formation of bony tissue. The cancellous bone which is developed 

 during these processes forms the mid-portion of the bone or diploe, 

 the outer walls of the flat bone being formed by periosteal ossifi- 

 cation as in the enchondral bones. 



