INSENSIBILITY OF BONES. 151 



essence, so hard and durable as to render any such 

 supply of nourishment and change of parts alto- 

 gether unnecessary. But if we look for a moment 

 to the advantages consequent upon this order of 

 things, we shall see abundant reason to abandon 

 such an opinion. 



It is only by means of the processes of growth 

 and renewal that the bones can adapt themselves 

 to the wants and state of the system. If the bones 

 were not endowed with the principle of life, the stat- 

 ure of the infant must have been that of the future 

 man. Or even supposing the osseous system to have 

 grown to maturity, and then remained unchanged, 

 the withered form of old age would necessarily have 

 been oppressed and overcome by the large and mas- 

 sive bones which the vigorous muscles of manhood 

 alone could easily put in motion. Had the bones 

 been created unsusceptible of internal change and 

 unendowed with life, it is obvious, that when broken 

 by accident they must have remained for ever dis- 

 united, and therefore an encumbrance instead of an 

 assistance to the animal. But from possessing blood- 

 vessels of their own to supply them with nourish- 

 ment, and nerves to give power of action to those 

 blood-vessels, the very irritation of the broken ends 

 is made to serve the purpose of increasing the vital 

 powers of the injured parts, and producing that ex- 

 citement which is necessary for the formation of a 

 new bond of union, and for filling up the gap that 

 would otherwise have remained. 



In a state of health, the bones are insensible to 

 pain ; and here, also, the most provident benevolence 

 appears. For, surrounded as they are by the softer 

 and more sensitive parts, these afford them ample 

 protection, while their insensibility enables them to 

 act, for any length of time, without weariness or 

 pain. But when a severe accident occurs to break 

 them asunder or destroy their texture, pain then be* 

 comes their kindest guardian, and the surest pro- 



