Chap. 4.] t 93 I 



CHAP. IV. 



x 



STRUCTURE OF THE BONES. 



Bones con/i/} of Fibres ; cellular. The Marrow. Wafte of Bone In 

 old Age. Kpipbjfes.'PerioJleum, Progrefs of Oj/ificatioK. 

 Articulation. 



TH E body, as Hippocrates long ago remarked, 

 is a circle ; and therefore at whatever poinc 

 "we were to begin the defcription, wefhould ultimately 

 be equally led, by the connexion of parts, to the confi- 

 deration of the whole. Since the bones, however, may 

 be confidered as the bafis of the body, on which the 

 other parts depend for fituation and fupport, it appears 

 moil eligible in the firft place to confider their ftrufture 

 and ufes. 



The bones con fift of fibres, distributed in lamella or 

 plates ; thefe plates are not clofely applied to each 

 other, but, with the intervention of tranfverfe fibres, 

 conftitute cells. The cells are diflributed through the 

 fubftance of all the bones, but are uniformly moft re- 

 markable in the center, and on the fur face of the harder 

 bones are fo fmall as not to be diftinctly perceptible 

 without the aid of glafies. 



The marrow which fills the cavities of the bones is a 

 fat oily fubftance, contained in a fine and tranfparent 

 membrane, which receives numerous blood-veffels, 

 and is fupporteci by the filaments of the reticuiar fub- 

 ftance of the bones. If the different parts of a bone 

 are pbferved, it is found that where the diameter of the 

 bone is the leaft, there the fides arc thickeft and 

 moft compadj where the diameter is greateft, 



which 



