242 PHYSIOLOGY AND HEALTH. 



585. As the child grows, the lime is added, and the bones 

 become stronger, until the full maturity of life, when the 

 composition is the most perfect and the frame has the great- 

 est power of resistance, and will bear the hardest blow and 

 support the greatest burden without suffering. This state 

 continues until the approach of old age. Then the gelatine 

 diminishes and the lime preponderates ; the bones conse- 

 quently become brittle, and are more easily broken. 



586. The bones are supplied with blood-vessels and blood; 

 they are subject to growth and jdecay, to deposition 

 of new matter and absorption of the old particles, as the 

 other textures are. The change is shown in the experi- 

 ment of feeding sheep with some coloring matter. ( 248, 

 p. 114.) The bones of these animals were red while they 

 ate madder, and became white when they returned to the 

 usual food of hay and grain. In the first,cae, the red par- 

 ticles of the food were deposited in the bpnes unchanged. 

 In the second, these red particles had been absorbed, and 

 others, of the natural color, had been deposited in their stead. 

 The bones are supplied with nerves, and are therefore sus- 

 ceptible of pain under some circumstances. In some states 

 of disease, the patient complains of pain in his bones. 

 When the bone is sawed in amputation, it does not seem 

 to suffer ; but, if it becomes inflamed, the pain is very 

 severe. 



587. When a bone is broken^and the parts divided, the 

 textures of the severed ends repair, the breach. They, in 

 the first place, throw out at the broken extremities a quantity 

 of adhesive matter. This unites the parts with a soft bond, 

 which would prevent their being drawn asunder, but would 

 not prevent their bending at this place. After this flexible 

 union is formed, the blood-vessels throw into it earthy 

 matter, which combines with the jelly, and forms a new 

 bone, of composition similar to that of the original bone. 

 At first, this new structure is not quite so firm as the old ; 

 but nature provides for this by increasing the quantity of new 

 deposit, and making a bulbous projection all around ; thus 



