CHAPTEK VII. 



THE CONNECTIVE SUBSTANCE GROUP. Continued. 

 BONE. 



THERE are two principal varieties of bone known to anato- 

 mists, the compact and the cancellous or spongy. The former 

 is found in the shafts of all the long bones of the body and 

 along the outer surface of all the short and flat bones. The 

 latter occurs in the articular extremities of all long bones and 

 in the interior of all short and flat bones. 



Compact tissue consists of an unyielding, almost inelastic, 

 massive framework, which is traversed by networks of blood- 

 vessels and -lymphatics, and perhaps by nerves. The dense 

 organic substance forming the groundwork of all bone ossein 

 is in reality nothing but a form of connective substance 

 almost precisely resembling ordinary fibrous tissue, but which 

 is evenly infiltrated with minute molecules of the carbonates 

 and phosphates of lime and some other inorganic salts. These 

 insoluble matters are so thoroughly intermixed with the fibrous 

 tissue that they give it great solidity, though at the same time 

 they restrict its flexibility, and therefore increase its suscepti- 

 bility to fracture. 



Like other forms of the connective-tissue series, it contains 

 corpuscles that are disposed in a regular way between lamel- 

 lae, which here correspond to the fascicles of fibrous tissue. The 

 province of these corpuscles is doubtless the same as that of 

 other connective-tissue corpuscles, viz., to preside over the nu- 

 trition of the tissue in which they are found. 



After decalcification by strong acids, such as the nitric or 

 muriatic, if the residue be boiled it will yield gelatin or chon- 

 drin. 



These corpuscles that have just been described are not al- 



