64 



THE CONNECTIVE TISSUES 



secondary })ony matrix in the form of concentric lamella^, one within 

 the other, surrouncHng a central cyhnch'ical cavity containing some 

 osteogenic tissue, blood vessels, and nerve fibers. Such a series of 

 lamellae with the ca\'ity just described is called an Haversian sys- 

 tem; the lamellie are Haversian lamelhe and the central cavity is 



Fig. 35. — Phc)tograi)h of a portion of the diaphysis .shown in Fig. .Hf). The arrange- 

 ment of the cartilage cells, the resorption of the matrix between the adjacent cells 

 and the extension of marrow tissue are shown in studying from top toward the bot- 

 tom. In the central and lower portion bony spicules have been deposited by the 

 osteoblasts; at the right (dark portion) the periosteum is depositing layers of bony 

 matrix in the same manner as in the case of membranous bone. A ijrojection of vas- 

 cular tissue (light area beginning in middle of right margin) is shown extending from 

 the perichondrium through the periosteal bone into the central marrow tissue. 



the Haversian canal. These systems run ])rimarily lengthwise of the 

 bone, but there are lateral connections between adjacent Haversian 

 canals. Many small canals without lamelhe extend fi'om the 

 surface of the bone into Ilavei'sian canals and similar canals extend 

 from the central marrow ca\'it\' outward connecting with Ilaxersian 



