238 PHYSIOLOGICAL CHEMISTRY. 



III. Bone. 



The bony structure proper, when free from other formations 

 occurring in bones, such as marrow, nerves, and blood-vessels, con- 

 sists of cells and a basic substance. 



The cells have not been closely studied in regard to their chemi- 

 cal constitution. On boiling with water they yield no gelatine. 

 They contain no keratin, which is not usually present in the bony 

 structure (HERBERT SMITH), but they may contain a substance 

 which is similar to elastin. 



The basic substance of the bony structure contains two chief 

 constituents, namely, an organic substance, ossein, and the so-called 

 bone-earths enclosed in or combined with it. If bones are treated 

 with dilute hydrochloric acid at the ordinary temperature, the lime- 

 salts are dissolved and the ossein remains as an elastic mass, pre- 

 serving the shape of the bone. This ossein is generally considered 

 identical with the collagen of the connective tissue. The ossein in 

 the bones of certain aquatic fowls and fishes can hardly be consid- 

 ered identical with this collagen (FREMY). 



The inorganic constituents of the bony structure, the so-called 

 bone-earths, which remain after the complete calcination of the 

 organic substance as a white, brittle mass, consist chiefly of calcium 

 and phosphoric acid, but also include carbon dioxide and, in 

 smaller amounts, magnesium, chlorine, and fluorine. Alkali sul- 

 phate and iron, which are found in the bone-ash, do not seem to 

 belong exactly to the bony substance, but to the nutritive fluids or 

 to the other constituents of bones. 



The opinions of investigators differ somewhat as to the manner 

 in which the mineral bodies of the bony structure are combined 

 with each other. Chlorine and fluorine are present in the same 

 form as in apatite (CaFl 2 , 3Ca 3 P 2 8 ). Proceeding from the chlorine 

 and fluorine, it is possible that the other mineral bodies form the 

 combination 3(Ca 3 P 2 8 )CaC03. 



Analyses of bone-earths have shown that the mineral constit- 

 uents are related to each other in nearly constant proportions, and 

 this applies not only to man but also to the different animals. As 



