34 THE CALLUS. 



hardened by lime being deposited in it. It forms a sort 

 of natural splint, and strengthens the bone until the 

 ends have firmly grown together. Then it is slowly 

 absorbed, and after a few months hardly a trace of 

 it is left. The callus iray be compared to the metal 

 band which is used to hold together the two parts of 

 a broken umbrella-handle. Inside the callus, new bone 

 slowly forms in the gristly layers between the broken 

 ends, and unites them. The surgeon usually removes 

 his artificial splints when the callus has become well 

 developed. 



