CONNECTIVE TISSUE. 



229 



by Troja, in 1814). They traverse the outer peripheral system 

 of lamellae, sometimes in the form of single cords, sometimes as 

 a broad reticulum, but often they are entirely absent. 



FIG. 89. TIBIA OF A GROWN DOG. CORTICAL PORTION, LONGITUDINAL 

 SECTION. CHROMIC ACID SPECIMEN. 



S, Haversian system of lamellae, containing the bone-corpuscles, C, with their transverse 

 offshoots; M, central medullary, so-called Haversian canal, containing a capillary blood- 

 vessel ; I, interstitial bone-tissue. Magnified 500 diameters. 



In fully developed bone the periosteum consists of two layers, 

 the outer fibrous portion being supplied with numerous blood- 

 vessels, which inosculate directly with the blood-vessels of the 



