56 SKELETON. 



have their texture more or less approximated to the spongy tis- 

 sue. Mr. Velpeau (Anat. Chirurg.) says, that in the amphithe- 

 atres of Paris, he has often cut easily with a scalpel, the ends of 

 the femur, tibia, humerus, the bodies of the vertebrae and the 

 tarsal bones, when there was apparently no morbid lesion in the 

 skeleton. 



SECT. II. COMPOSITION OF BONES. 



The bones under every modification of shape and mechanical 

 arrangement, are constituted by precisely the same elementary 

 matters : the principal of which are an animal and an earthy 

 substance, in intimate combination. Their minute analysis, 

 according to Berzelius, when they are deprived of water and 

 of marrow, affords 32 parts of gelatine, completely soluble in 

 water; 1 part of insoluble animal matter; 51 parts phosphate 

 of lime; 11 carbonate of lime; 2 fluate of lime; 1 phosphate 

 of magnesia; 1 soda and muriate of soda. There are some 

 other ingredients manifested in the analysis of Fourcroy and 

 Vauquelin, as iron, manganese, silex, alumine, and phosphate 

 of ammonia. The relative proportion of the above ingredients 

 is not uniformly the same, as the bones of the cranium, and the 

 petrous portion of the temporal, in a remarkable degree, have 

 more calcareous matter in them, than the other bones of the 

 same skeleton. There is also a considerable diversity in indi- 

 viduals, according to their age and to certain morbid affections. 



The earthy matter gives to bones their hardness and want 

 of flexibility, and is easily insulated from the other by combus- 

 tion; which, in destroying the animal part, leaves the earthy 

 in a white friable state, but preserving the original form of the 

 bone. If the heat be of a high degree, the calcareous part 

 becomes vitrified, and its cells are blended by fusion. The 

 action of the atmosphere, long continued, also divests the bones 

 of their animal matter, and the calcareous then falls into a 

 powder. If the bones be kept beneath the surface of the 

 ground, by which they are less affected by changes in tempe- 

 rature and moisture, the animal matter remains for an immense 

 number of years. I have seen in the Hunterian Museum of 

 London, preparations of the teeth of the Mastodon or Mam- 

 moth, in which the animal matter was exhibited entire, notr 



