406 



THE SUPPORTING TISSUES. 



which have thus far been considered, bone-tissue apparently con- 

 tains no glucoproteids. 



The function of the bone-tissue, as the principal supporting tissue 

 of the body, finds its expression in the preponderance of the mineral 

 constituents over the organic solids, and it is interesting to note that 

 the ratio between the two is fairly constant, not only in different 

 bones, but also in different animals. These salts are largely repre- 

 sented by calcium phosphate and carbonate, which impregnate the 

 entire matrix. In addition, we find magnesium phosphate and 

 small amounts of calcium chloride, calcium fluoride, potassium and 

 sodium salts, and a little iron. Of the mariner in which the differ- 

 ent salts are combined with each other, nothing definite is known, 

 but we may possibly assume, with Gabriel, that the composition of 

 the bone-ash, as well as the tooth-ash, can be represented by the 

 formula [Ca ? (PO 4 ) 2 + Ca^PgO^ + H 2 O], in which 2 to 3 per cent, 

 of calcium is replaced by magnesium, potassium, and sodium, and 

 4 to 6 per cent, of the phosphoric acid by carbonic acid, chlorine, 

 and fluorine. 



Whether or not the mineral constituents of the bone exist in com- 

 bination with the organic components of the tissue has not as yet 

 been definitely ascertained, but does not appear improbable. 



An idea of the quantitative distribution of the different salts in 

 different animals and bones may be formed from the accompanying 

 analyses. The figures have reference to 100 parts of bone-ash 

 (Zalefsky) : 



Calcium phosphate (Ca 3 (PO 4 ) 2 ) . . 



Magnesiu m phosphate ( Mgg( PO 4 ) 2 ) . 



Calcium in combination with carbon 



dioxide, chlorine, and fluorine . . 



Carbon dioxide l 



Chlorine 



Fluorine 2 . . 



Small flounder (ash in general) . 



Man (ash in general) 



Man (humerus) 



Ox (femur) 



Goose (ash in general) 



Rabbits, varying in age between 

 one day and four years (general 

 ash) 



Human. 



83.89 

 1.04 



7.65 

 5.73 

 1.80 

 2.30 



Calcium 

 oxide 

 (CaO). 



53.13 

 52.83 

 51.31 

 51.28 

 51.01 



51.91-52.89 39.78-42.20 0.83-1.38 



The variations in the amount of bone-ash, as a whole, in different 

 bones of the same animal, are seen in the following table (Fremy) r 



1 These figures are somewhat too low, as a certain amount of carbon dioxide escapes 

 during the incineration of the bone. 



2 According to Gabriel, the amount of fluorine does not exceed 0.1 per cent., and is usually 

 less than 0.5 per cent. 



