162 THE OSSEOUS TISSUE. 



Cartilage, 32.17 Fluoride of Calcium, 2.00 



Insol. animal matter, 1.13 Phos. of magnesia, 1.16 

 Phosphate of lime, 51.04 Soda, chlo. of sodium, 1.20 

 Carbonate of lime, 11.30 



Vanquelin and Fourcroy have also detected iron, man- 

 ganese, silex, alumina, and phosphate of ammonia. 



These ingredients are found in bone every where, and 

 under all circumstances, though the relative proportion of 

 the respective parts often varies, not only in different bones 

 but at different times in the same bone. 



The bones of the cranium, especially the petrous portion 

 of the temporal, furnish more calcareous matter than the 

 rest of the bones of the same skeleton. To the predomi- 

 nance of the earthy matter, in the aged, do the bones owe 

 their great brittleness ; while, on the contrary, in chil- 

 dren, it is deficiency of the earthy and predominance of the 

 animal matter, which make the bones at that age so very 

 flexible. 



The bones collectively constitute the skeleton. When 

 they are united by their own ligaments, left for that pur- 

 pose, the skeleton is a natural one. When they are con- 

 nected by wire or any other foreign substance, it is artificial. 



The skeleton is divided into the head, trunk and extrem- 

 ities. The bones composing these great divisions are again 

 divided, according to their form, into the long, the flat, or 

 broad, the short and the mixed. 



Specimens of the long bones are found in the extremities, 

 as in the thigh, leg and arm. The flat compose the 

 cranium and pelvis. The short are seen in the wrist, in- 

 step and spine ; while the sphenoid and temporal bones 

 present examples of the mixed. 



The number of bones in the human body is not precisely 

 agreed upon by anatomists, some making more and others 

 less, owing to the period of life at which the calculation is 

 made. The younger the subject, the more numerous are 

 the bones, and as age increases, the bones run into each 

 other and become fewer in number. Taking the adult pe- 

 riod as the standard, the whole number may be estimated 



