BONE. 



the process of formation of new bone 

 is most active ; and the earthy mat- 

 ter precipitated from the blood car- 

 ries down with it the colouring 

 matter of the madder. 



The blood-vessels 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 chondrine, as in cartilage), 

 with phosphate of lime, small quan- 

 tities of carbonate of lime, carbonate 

 of magnesia, fluoride of calcium, and 

 sometimes a little oxide of iron and 

 magnesia. 



By digesting bone with dilute 

 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. 



Fig. 73. 



r.:. 



Magnified 20 diameters. 



Perpendicular section of the margin of the shaft of 

 the femur of a child, two weeks old, showing the calci- 

 fication of cartilage, a, cartilage and its cells ; 6, 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. 



Magnified 300 diameters. 



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

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

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

 cellular substance ; d. 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. Earthy matter is then deposited 

 in the cartilage, in a finely granulated form 

 (fig. 73) ; thus we have calcified cartilage 

 but not bone. 



Absorption of the calcified cartilage next 



1 1 1 1*11 11 i 



takes place, by which larger cancelli and 

 canals are formed. Lastly deposition on the 



