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HUMAN BIOLOGY 



growth. The mineral matters m our foods are made soluble and 

 are then supplied by the blood to the bone cells, and these in turn 

 convert this mineral matter into the hard intercellular substance. 



216. Effect of pressure on bones. — Tight-fitting clothing is a 

 most important factor in modifying permanently the shape and po- 

 sition of bones. Normal growth cannot be attained if the skeleton 

 is subjected to pressure. Yet this important principle of hygiene is 

 constantly violated by women who wear tight-fitting clothing about 



A = Normal position of organs. B = Position of organs after lacing. 

 Fig. 46. — Effect of tight lacing on the organs of the chest and abdomen. 



the waist. Baneful fashion is often followed even in youth, when the 

 skeleton yields- readily to pressure. The result is that the ribs are 

 permanently bent downward and inward, thus interfering seriously 

 with the action of the abdominal organs (Fig. 46). High-heeled 

 shoes are another frequent cause of deformity. They reduce the 

 spring in- the arch of the foot and throw too much of the weight of 

 the body upon the tips of the toes, and this is likely to injure the 

 arch of the foot. Shoes with narrow toes should never be worn, 

 since by this means the foot is deformed. 



217. Fractures. — Any sudden strain or blow upon a bone is 

 liable to cause a break or a fracture, especially in later life, when the 



