396 



CHAPTER XI. 



THE COMPONENT PARTS OF THE ANIMAL BODY. 



The Bones. 



THE bones are the least destructible of all the parts of the 

 organism. Under favorable circumstances they remain as un- 

 changed as mere inorganic matter, and the amount of cartilage 

 has been found unaltered in bones three thousand years old. 1 



The external surface of bone is surrounded by a membrane 

 richly endowed with nerves and vessels the periosteum, which, 

 as well as the cartilaginous portion, can be converted, by boil- 

 ing, into gelatin. The interior of the cylindrical bones is lined 

 in a similar manner : the flat and short thick bones are, how- 

 ever, filled in the interior with delicate lamella? arranged so as 

 to present a cellular appearance : in the flat bones, this is 

 termed the diploe. If a bone is suspended in dilute hydrochloric 

 acid at a low temperature, all the earthy matter becomes gra- 

 dually dissolved and the mere cartilage remains, retaining the 

 precise form of the original bone. It is supple, transparent, 

 and soft, but on drying it becomes of a darker colour, hard, 

 and somewhat contracted. When boiled it becomes rapidly 

 converted into gelatin, leaving the fibrous tissue and the vessels 

 of the bone unacted on. These vessels may be exhibited by 

 leaving the bone in dilute hydrochloric acid till about one half 

 of the earthy matter is dissolved : it must then be washed with 



1 This has been observed in the bones of human and animal mummies discovered 

 in Egyptian sepulchres. Apjohn and Stokes found in the bones of an extinct gigantic 

 elk, 48-87 of ordinary cartilage, combined with 43*45 of the phosphates of lime and 

 magnesia with fluoride of calcium, and 9-14 of carbonate of lime, &c. In the teeth 

 of an Egyptian mummy, Lassaigne found 29g of organic matter ; and in the teeth of 

 a fossil bear, 14 of cartilage and 70 of phosphate of lime. Gimbernat prepared an 

 edible jelly from the bones of the Ohio mammoth. 



