THE CONNECTIVE TISSUES. 125 



ous tissue and by a partial absorption of the larger ones, the 

 primary marrow spaces thus becoming secondary marrow spaces, or 

 Haversian spaces. The osteoblasts now arrange themselves in layers 



Connective- 

 tissue. 



Outer fibrous - 

 layer of 

 periosteum. 



Osteogenetic 



layer of 

 periosteum 



Osteoblasts 



space. 



Blood-ves-_ 



sel. 



Osteoblasts.- 





I 



f J"A : 



matrix. ' 

 Osteobiasts.^ 



Fig. 91. From a cross-section of a shaft (tibia of a sheep) ; X 55- I n the lower 

 part of the figure is endochondral bone-formation (the black cords are the remains of the 

 cartilaginous matrix) ; in the upper portion is bone developed from the periosteum. 



about the walls of the Haversian spaces and deposit lamella after 

 lamella of bone matrix, concentrically arranged, until the large 

 Haversian spaces have been reduced to Haversian canals. During 



