254 COMPOSITION OF BONE. 



Fig. 109 is a photograph of a transverse section of part of human fe- 

 mur, showing the haversian canals surrounded by their concentric lamel- 

 la, lacuna, and canaliculi. The complete perviousness of the structure 

 is demonstrated. 



Fig. 109. Fig. 110. 



Transverse section of bone, magnified 50 diameters. Lacunae and canaliculi from frontal bone. 



Fig. 110, lacunae and canaliculi of human frontal bone. 



In chemical constitution, bone may be considered to be composed of 

 Chemical com- two P ort i ns > organic and mineral : the former is gluten, and 

 position of in the latter phosphate of lime greatly predominates, as the 

 )ne> following analysis by Berzelius shows : 



Analysis of Bone. (Berzelius.) 



Cartilage (or gluten) 32.17 



Blood-vessels 1.13 



Phosphate of lime .51.04 



Carbonate of lime 11.30 



Fluoride of calcium 2.00 



Phosphate of magnesia 1.16 



Soda, chloride of sodium ...*..... ,. 1.20 



100.00 



An instructive separation of bone into its leading constituents may be 

 Se aration of accom pli sne d by the action of hydrochloric acid or by cal- 

 its organic and cination respectively. When a bone is soaked in dilute hy- 

 y ases. d r ochloric acid for a due length of time, its mineral constitu- 

 ent is removed, and the organic gluten is left in the shape of the original 

 bone ; or, if the bone be calcined in the open fire with free access of air, 

 the organic material is consumed and the mineral material remains. A 

 more . critical examination shows that these constituents are not merely 

 associated together they are, in reality, chemically combined. 



The different degrees of softness and hardness which bones from dif- 

 ferent animals present depend very considerably on the amount of wa- 

 ter they contain. The gluten is doubtless, in all instances, derived from 



