BONE. 



[ 112 ] 



BONE. 



the process of formation of new bone 

 is most active ; and the earthy mat- 

 ter precipitated from the blood car- 

 ries down Avith it the colouring 

 matter of the madder. 



The l)Iood-Yessels of bone which 

 are distributed to the marrow (the 

 nutrient vessels), enter particular ca- 

 nals on the external surface ; whilst 

 those connected with the Haversian 

 canals are derived from the perios- 

 teum and from those of the marrow, 

 The two sets anastomose freely. 



Chemically, bone consists of gela- 

 tine (not choudriue, as in cartilage), 

 ■with phosphate of lime, small quan- 

 tities of carbonate of lime, carbonate 

 of magnesia, fluoride of calcium, and 

 sometimes a httle oxide of iron and 

 magnesia. 



13y digesting bone with dilate 

 muriatic, chromic, or picric acid, the 

 inorganic matter is removed, and 

 by treatment with solutions of alka- 

 lies or incineration, the inorganic 

 substance or so-called cartilage may 

 be separated. 





.J 



Fig. 74. 



^ t,'^ •■ 



't^' 





f 



fi-\ 





Magnified 20 diameters. 



Perpendicular section of the margin of the shaft: of 

 the femur of a child, two weeks old, sliowing thp calci- 

 fication of cartilage, a, cartilage and its cclis ; ft, mar- 

 gin of calcification; the dark stripes represent the cal- 

 cification of the intercellular substance, which precedes 

 that of the cartilage-cells, indicated by the lighter por- 

 tions ; c, compact calcified layer near the calcifying 

 margin ; e, cancelli formed by the absorption of the 

 calcified substance. 



O/^^i.,;.,//-^!! r\J A I \im 



Magnified 300 diameters. 



Section of the margin of calcification of the condyle of the femur 

 of a child two years old, afliected with rickets, a, cartilage-cells, 

 single and multiplying, in rows; 6, e, more or less striated inter- 

 cellular substance ; rf, cartilage-cells at the very commencement 

 of secondary deposition; e, the same in a more advanced state, 

 ■with greatly thickened walls, indications of the canaliculi, and 

 commencing deposition of calcareous salts in the walls, hence 

 their darker colour, the nuclei still distinct; f, still more deve- 

 loped and calcified cells imbedded in the intercellular substance 

 g, which is also becoming calcified. 



In the development of bone, first the cells 

 of the (primary) cartilage multiply by en- 

 dogenous cell-growth, forming longitudinal 

 rows or irregular heaps. These fuse and 

 liquefy, so as to produce canals and cancelli, 

 in which blood-vessels and medulla are 

 formed. F.arthy matter is then deposited 

 in the cartilage, in a fiuely granulated form 

 (tig. 73) ; thus we have calcified cartihige 

 — but not bone. 



Absorption of the caloified cartilage next 

 takes place,, by which larger cancelli and 

 canals arc formed. Lastly deposition on the 



