CONNECTIVE TISSUE. 



227 



tying at very acute angles, will make their systems of lamellae lie 

 close together ; but if ramifying at less acute angles, will leave in- 

 terstices filled with distinctly lamellated intermediate bone-tissue. 

 In order to render the formation of cortical bone easily understood, 

 the following illustration is often used : take a number of matches, 

 around each of which is twined a cord, and wind the cord around 

 the bundle, the match representing the Haversian canal, the twines 

 around each match the systems of lamellae, and the twines around 

 the bundle the peripheral lamellae. This comparison holds good, 

 of course, only for the case in which the intermediate bone-tissue 

 is absent. The law, however, according to which the peripheral 



FIG. 88. TIBIA OF A GROWN DOG. CORTICAL PORTION, TRANSVERSE 

 SECTION. CHROMIC ACID SPECIMEN. 



V, Haversian system of lamellae, containing the bone-corpuscles, C, with their radiating 

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

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



and the Haversian systems of lamellae are formed, has not yet 

 been explained. 



With higher amplifications of the microscope each Haversian 

 system proves to be composed of a number of concentric lamellae, 

 which are not perfect throughout the system. Both within and 

 between the lamellae, bone-corpuscles are visible with radiating 

 offshoots, a number of which traverse the lamellae, without being 

 in direct connection with a bone-corpuscle. (See Fig. 88.) 



