BONE. 



45 



Gray states that the organic constituent of bone forms about 

 33 per cent., and the inorganic 66.7 per cent. He quotes the fol- 

 lowing analysis of Berzelius : 



Organic matter ... 



. Gelatin and blood-vessels . 



(Phosphate of lime . . . . 

 Carbonate " .... 

 Fluorid of calcium ... 

 Phosphate of magnesium . 

 Soda and chlorid of sodium, 



33.30 per cent. 



51.04 



11.30 



2.00 



1.16 



1.20 



The organic constituents are ossein, also called collagen ; elas- 

 tin, proteids, and nuclein form the bone-corpuscles, with a small 

 quantity of fat. The inorganic constituents are calcium phosphate, 



\ 





4 



- 



FIG. 35. From a section through human red bone-marrow : a, /, normoblasts ; 

 6, reticulum ; c, mitosis in giant cell ; d, giant cell ; e, h, myelocytes ; g, mitosis ; 

 i, space containing fat-cells ; X 680 (Bohm and Davidoff ). 



carbonate, chlorid, and fluorid ; magnesium phosphate, sodium 

 chlorid, and some sulphates. Of these inorganic constituents, 

 calcium phosphate exists to the amount of 83.88 per cent., and 

 calcium carbonate to the amount of 13 per cent. 



Development of Bone. Ossification, the process by which bone 

 is formed, occurs in two forms : intramembranous and intracarti- 

 laginous or endochondral. The subperiosteal variety described by 

 some authors is, in all essential particulars, identical with the 

 intramembranous. By the intramembranous are formed the 

 parietal, frontal, and upper portions of the tabular surface of the 



