CONDITIONS OF HEALTH IN BONKS. 159 



activity of nutrition, no perfection of development, 

 and no force of function. And hence, in partial ex- 

 ercise, there is always predominance of some part 

 over others ; the one too strong, the other too 

 feeble. In the muscular system, the arms of a 

 blacksmith, contrasted with those of a dancing- 

 master, are a sufficient illustration. 



This law of increased afflux of fluids and in- 

 creased nutrition to exercised parts, and of diminished 

 afflux and nutrition to inactive parts, is not only 

 highly important in its practical consequences, but 

 in exact and obvious accordance with the plainest 

 principles of reason. By this benevolent arrange- 

 ment, parts acting strongly receive large supplies, 

 and parts doing nothing are left in the state of 

 weakness befitting the demands made upon them. 

 To every one who sees the principle, it must appear 

 the height of folly to expect great nutrition and 

 great energy to follow inaction, and vice versd ; and 

 yet this is what, in ignorance, is daily looked for by 

 mankind at large. 



This law of exercise, as influencing nutrition and 

 function, is universal in its application, and applies 

 to the osseous as much as to any other system. If 

 the bones are duly exercised in their function of ad- 

 ministering to motion, then active nutrition goes on, 

 and they acquire dimensions, strength, and solidity. 

 If they are not exercised, the stimulus required for 

 the supply of blood to them becomes insufficient ; 

 imperfect nutrition takes place ; and debility, soft- 

 ness, and unfitness for their office follow in the 

 train. This cause of defective formation is most 

 active and most commonly seen in the bones of the 

 spine in growing girls, who are denied free exercise 

 in that part ; and the consequent weakness in the 

 bones and cartilages, as well as in the muscles, is a 

 very frequent cause of the swollen joints and cur- 

 vature in the bones of the limbs in young people, 

 which no subsequent care can ever remove. 



