7o 



SIXTH LECTURE. 



Let us then investigate these Haversian spaces. 



Our figure (Fig. 65), shows us three Haversian lamellar 

 systems. The two hatched ones (a, a), present inter- 

 nally an indented resorption line {b> b). New bone lamellae, 

 maintaining the outline, have been deposited on this. To 

 the right (c), a second liquefaction has overtaken the latter, 

 for which a new lamellar formation endeavors to compen- 

 sate. 



Fig. 65. — A human metacarpal bone in transverse section ; a*, a Haversian lamella system of 

 the ordinary variety ; a, a, two others which have undergone absorption internally (6, />), and thus 

 form Haversian spaces, which are rilled up by new lamellae ; c, supplementary absorption in one of 

 these with deposit of new bone substance ; d, irregular, and c, ordinary intermediate lamellae. 



Koelliker has ascribed to the multi-nuclear giant cells (Fig. 

 13), the property of dissolving the bone substance, and called 

 them osteoclasts. We do not share in this view. Between 

 the bone-producing osteoblasts of Gegenbaur and the bone- 

 destroying elements of the first mentioned investigator, transi- 

 tion forms exist. 



We hold fast to the absorption of the endochondral bone, 

 therefore, and now inquire into the particulars of the peri- 

 pherical reparation. This is produced by the periosteal bone ; 

 that is, the osteoid tissue, which is subsequently furnished 

 from the inner surface of the periosteum. 



An. eminent French observer, Oilier, informs us that the 

 detached living periosteum, whether it be retained in the body 



