BONE. 



37 



eral matters and examined in thin fragments, the osseous lamellae often 

 exhibit indications of the fibrous structure which they really possess, since 

 the bone- matrix consists of closely felted bundles of white fibres united by 



Interstitial lamellae 



Haversian canal 



Obliquely cut 

 Haversian canal 



FiG. 50. Longitudinal section of compact bone, ground and dried. X 70. , 



cement-substance. Within the Haversian lamellae the fibrous bundles cross 

 generally at right angles, but within the other lamellae they are placed less 

 regularly and more obliquely. 

 On examining decalcified bone, 

 either in section or after being 

 pulled apart,' bundles of fibrous 

 tissue are seen which penetrate 

 the outer circumferential lamel- 

 lae in a direction perpendicular 

 or oblique to the surface and 

 thus pin or bolt the layers 

 together. ' Such bundles, the 

 Perforating fibres of Sharpey, 

 are numerous in the lamellae 

 beneath the periosteum, from 

 the inner layer of which mem- 

 brane they are derived. The 

 perforating fibres consist of 

 bundles of fibrous tissue, with a variable number of elastic fibres; since they 

 are often imperfectly calcified, on drying they leave minute canals which 

 pierce the lamellae from the surface of the bone. Being produced by the 



Lacuna cut, 

 obliquely' 



FIG. 51. Portion of adjacent Haversian system cut trans- 

 versely. X 250. 



