MEDULLARY MEMBRANE OR INTERNAL PERIOSTEUM. 35 



The medullary matter in the large cavities of bones has a 

 strong resemblance to adeps. That which is in the cells, at the 

 ends of the long bones, appears more fluid. In young animals 

 it is slightly tinged with a red color. 



— The chemical properties of the adipose or medullary sub- 

 stance of the bones consist according to Berzelius of the fol- 

 lowing ingredients : 



Pure adeps or marrow - - - 96 



Membrane and blood-vessels - - - 1 



Albumen _ _ _ _ _ 



Gelatine > _ . _ 



Extractive and peculiar matter 



Water - - - - - 



100 



— The character of this substance differs somewhat at the dif- 

 ferent stages of life ; it is of a thin aqueous consistence and of 

 a reddish color in the infant ; of the consistence and presenting 

 after death somewhat the appearance of butter in the central 

 cavities of the bones, and of a red semi-fluid appearance in the 

 spongy tissue of the bones of the adult ; in old age it has some- 

 thing of a rancid smell, and is of a deep yellow color. The 

 adeps of the bones was supposed at one time to contribute to 

 the flexibility, tenacity, and nourishment of the bones, but it is 

 now generally believed to be deposited upon the same principles, 

 as fat in other parts of the body, when nutritive matter is super- 

 abundantly elaborated by the digestive organs, and is held in 

 reversion, as an aliment for the future wants of the economy, 

 during temporary inanition from sickness or other causes. 

 — The deposit of fat in bones is not universal among animals. 

 In birds the central cavity of the long bones, is filled only with 

 air which is introduced into them from the lungs, and serves 

 greatly to diminish their specific gravity, and facilitates their 

 evolutions in the atmosphere. 



— It is found in great quantity in the bones of the head of the 

 physeter macrocephalus, or sperm whale, far out of the pro- 



