BONES, MUSCLES, EXERCISE, AND REST. '243 



the bone is at the place of junction larger than either portion 

 of the shaft, above or below. When, in the lapse of time, 

 this new bone becomes condensed, and as strong as the old 

 bone, then the external deposit is absorbed, and the whole 

 shaft is nearly restored to its original form. 



588. The process of absorption and deposition of the par- 

 ticles of bone is shown in their change of shape ; as when 

 a tumor or enlargement of the arteries presses upon the ribs 

 within, and causes some parts of them to spread ; or as when 

 the close dresses press upon the same bones without, they 

 contract to meet the necessity of the case. ( 340, p. 150.) 



589. The bones grow larger and stronger by use, like the 

 other systems. Exercise of the parts quickens the cir- 

 culation and increases their nutriment. Disease and inaction 

 weakens them. If any one in good healtn* should lie upon 

 his bed for a long period, months or years, at the end of 

 this time he would not find it easy even to stand. The bones 

 would not easily support his weight. The exercise of the 

 bones favors the deposition of the earthy particles ; and for 

 this reason the bones of the laborer are dense and hard. 

 They have the due proportion of the animal matter and of the 

 earthy matter in their composition, and have, consequently, 

 great strength. But those who are unaccustomed to labor, 

 or even exercise, have not the full proportion of lime in their 

 bones, nor the strength that belongs to the working man. 



590. The bones in early life, being more gelatinous and 

 earthy, are consequently weak ; and the child, although able 

 to exercise, is incapable of hard labor. If he is put to hard 

 work, the deposition of the earthy matter is hastened, and the 

 bones become consolidated before they attain their full size ; 

 and the boy, not being allowed sufficient time for growth, be- 

 comes a stunted man. The bones of the child require more 

 care for their shape and their growth than those of the man ; 

 and if not supported, or if made to bear too great weight, 

 they are liable to* become distorted. In sitting, the child 

 should either find rest for the entire thigh bone, from the hip 

 to the knee, upon his chair or bench, or the lower part should 



