THE FRAMEWORK OF THE BODY 27 



13. The Growth of Bone. Bone, like all the other tissues of 

 the body, is constantly undergoing change, old material being 

 withdrawn, to make room for a fresh supply. This change 

 has been shown conclusively by experiments. If an animal be 

 fed with madder a red coloring matter for a day or two, 

 the bones soon become tinged ; then, if the madder be discon- 

 tinued for a few days, the original color returns. If, however, 

 this material be alternately given and withheld, at short inter- 

 vals, the bone will be marked by a succession of red and white 

 rings. In very young animals, all the bones become colored 

 in a single day ; in older ones, a longer time is required. The 

 process of waste and repair, therefore, is constantly taking 

 place in this hard substance, and with astonishing rapidity. 



14. The Repair of Bone. Nature's provision for uniting 

 broken bones is very complete. At first, blood is poured out 



female form rests in the side-saddle will cause the spine to become 

 curved." To avoid this, it is important for young ladies to ride occasion- 

 ally on the opposite side of the horse. Another frequent cause of curva- 

 ture of the spine is the use of the sewing-machine, especially among needy 

 seamstresses, whose bread frequently depends on the almost unceasing 

 labor of their hands and feet, while sitting in a constrained position. 

 Soon after croquet became a favorite amusement among the fashionable 

 young ladies of England, it was noticed that the bent position assumed 

 during the time the mallet is used, caused a certain deformity, to which 

 was given the name of the "croquet curvature." The use of high heels 

 on boots and shoes of children, by throwing the weight of the body too far 

 forward, on the front of the foot, and destroying the natural poise of the 

 body, acts an important part in causing the spine to become crooked. 

 By many this crooked position is considered to be largely a school-room 

 disease, for the reason that children often are compelled to sit, and write 

 or study, in a bent posture ; but there must be other causes for it, since it 

 has been found that it is almost exclusively a female deformity. Over 

 eighty-four per cent, of the cases is stated by one writer to be among 

 girls. But inasmuch as the majority of these cases begin during the 

 years of schooling from the ages of six to fourteen great attention 

 should be paid to the position of the body during school hours, and ample 

 opportunity should be offered, by a regular system of gymnastics, to 

 counteract all the evil influences of the school-room posture. Heather- 

 Bigg on Deformities (in part). 



13. Change in bone? Example animal and madder. Rapidity of change in color? 

 Waste and repair ? 



14. How is a broken bone united V What becomes of the blood caused by the injury ? 

 What takes its place ? How long does it usually take for a broken bone to unite ? 



